"Mercator Origins": Sat Nav & Telemetry for Divers

Want to map your dive? Want to navigate like a pro? Even if you are vision-impaired, this will empower you to navigate our underwater world.

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This is a dive computer like no other and will be the most inclusive device for diving I can imagine. I want to enable people who are vision impaired or blind to enjoy the sensation and freedom of weightlessness, through audio and haptic/vibration navigation guidance.

The goal is to enable the diver (or snorkeller) to choose their dive/snorkel plan and have the console provide heading and distance guidance to each waypoint in real-time, whilst underwater, using visual and/or audio directions.

Diver location/depth and telemetry is uploaded to the internet and shown on a live dashboard, so there is a safety aspect too.

Stretch goals:

* Emergency messaging: diver to 911.

* Integrate a bone conductor transducer and a radio link to provide a personal audio commentary to the diver!

* Bubble audio analysis to monitor the diver's breathing rate. Optimise your breathing rate for the ultimate meditative dive experience!

* Integrate a heartrate monitor using a radio link

Purpose of the Project

Scuba diving is an activity which gives you a freedom, experience of weightlessness and an appreciation for our underwater world which is, in my opinion, second to none. Diving opens a world which we don't otherwise experience for ourselves and develops our appreciation for the precious ecosystems of our oceans and waterways. It's great for teaching our younger generations an appreciation for the marine environment and for the conservation of our planet's rich life and habitats. Diving is also a great healer, once trained and confident the feeling of being in the water can be a great improver for one's mental health. Your day-to-day worries melt away and are replaced by an in-the-moment experience.

Scuba diving can be enjoyed by many people who you might otherwise think would be excluded, including those who have disabilities. For example, The Handicapped Scuba Association trains instructors and accredits training centres where disabled people are supported through scuba diving training that is tailored to their individual needs. I would like to make it easier for people who are vision-impaired to feel a sense of empowerment by being able to scuba dive without needing to hold another diver's hand for guidance. This will give the opportunity to be independent and to enjoy an activity that perhaps they hadn't thought for a moment could be a possibility.

One of the challenges involved in scuba diving (and of course a paramount challenge for someone vision impaired) is successful navigation, whether in the sea or in a lake. This is important for everyone because it is critical to safe diving that you plan your dive properly and then you dive your plan. This is to be safe and to ensure that the dive has a purpose and is enjoyable for all.

Training lakes, including Wraysbury, Vobster and Stoney Cove, in the UK offer a diving experience which is in a controlled environment without currents or other hazards that are particular to the open ocean. They have a large number of sunken wrecks deliberately positioned on the lake bed, including boats, taxis, buses, even helicopters and large aeroplanes (such as the fuselage of a 737 Boeing jet). It's very cool to dive these features!

My closest dive lake is Wraysbury Dive Centre, near Staines, in the UK. There are over 50 features underwater and navigating between any two features is a feat I have never managed due to the sheer number of possibilities! Here's the map - quite a challenge, right!

The purpose of this project, which I have named Mercator Origins after the famous cartographer, is to enable the scuba diver to navigate between a set of features or waypoints underwater, with the diver's console instructing the heading and the distance to each target - updating and correcting in real-time according to the diver's movements.

For someone vision-impaired they will be assisted by audio directions, either spoken, as tones or as vibrations in the diver's console they hold. There will also be a Time of Flight sensor to alert the diver in case their are getting too close to the sea/lake bed or other obstacles that could be problematic if collided with. There will also be visual directions on the console, including heading, distance and a graphical indicator to show turn clockwise, turn anti-clockwise or go straight ahead.

Someone who is vision impaired quite possibly will have one or more of their other senses more attuned than someone without impaired vision, such as their sense of touch or their spatial/positional awareness (ie their position in space relative to other objects and to gravity). Someone who cannot see very well, or not at all, may well be able to use their hands (with gloves!) to reach out and feel the boat, the taxi, the bus, etc. and to imagine with great clarity the structure before them.

Therefore, a person does not need to be able to see to be able to enjoy safe scuba diving whilst navigating successfully between points of...

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Scuba Nav Partslist - submission.xlsx

Bill of Materials for one unit including float system, spool/cable, navigation pod and audio pod 2.

sheet - 15.44 kB - 10/10/2023 at 13:53


UI Screen Elements.png

PNG version of the Draw.IO diagram with detailed explanation of all information shown on each user interface screen.

Portable Network Graphics (PNG) - 1.83 MB - 10/10/2023 at 12:20


UI Screen Elements.drawio

Draw.IO diagram with detailed explanation of all information shown on each user interface screen.

drawio - 1.42 MB - 10/10/2023 at 12:20


Mercator Origins Displays and Controls.drawio

Draw.IO user interface guide for the Mercator Origins system.

drawio - 6.32 MB - 10/10/2023 at 12:19


Mercator Origins Displays and Controls.png

PNG version of the Draw.IO user interface guide for the Mercator Origins system.

Portable Network Graphics (PNG) - 2.95 MB - 10/10/2023 at 12:19


View all 19 files

  • 1 × Underwater Kinetics IP67 Ultrabox 408 IP67 waterproof yellow surface float box, dry to 5 metres, including lanyard. Contains 5V power supply, GPS and microcontroller to interface with the internet, and WiFi Hotspot/4G Hotspot for 4G mobile data.
  • 1 × USB Power Bank Place in the dry float box: power the float and navigation console electronics. Recommend 2500mAh minimum capacity.
  • 1 × WiFi hotspot device Place in the dry float box: either a mobile phone, with personal hotspot turned on, in the float (dry!) box or use a MiFi-type data hotspot (eg by TP-Link)
  • 1 × Hose Strain Relief Boot (eg Beaver brand) A yellow, rubber strain relief boot for the cable connection on the surface float box.
  • 1 × Nite-ize S-Biner size #3 or #4 A double sided caribiner type of clip used to tie the cable and lanyard of the float box when transporting the unit. Also used underwater to tie off the cable at depth.

View all 56 components

  • Here’s my YouTube Maker’s Channel and GitHub Code Repos

    Mark B Jones06/02/2023 at 09:23 0 comments

    I have 20 or so more videos covering this project in the queue awaiting (rough) edit and upload in the pipeline including the Gozo sea trials, but for now there’s around 30 videos uploaded for your delectation!

    Scuba Hacker’s Sat Nav YouTube Channel

    Amongst the many code repos/projects on my github, these are the ones for Mercator Origins: (all named after sharks. There are 4 computers - 7 CPU cores - now independently working to implement this project!)





    Scuba Hacker’s Githhub Code Repos

  • Mercator Origins - Audio Guidance Enabled - Final Assembly

    Mark B Jones05/30/2023 at 11:58 0 comments

    The completed assembly - navigation console and audio module, with surface float.

    And from another vantage point

    Side view of the spool in close up

    The navigation console (powered through the cable from the float)

    The audio guidance module (independent power supply)

  • Behold: The Audio Navigation Module

    Mark B Jones05/30/2023 at 11:18 0 comments

    This is the back of the audio module. You can see from top left, clockwise:

    1. The surface exciter that vibrates the enclosure to produce sound underwater.

    2. The Beetle ESP32-C3 (RISC-V) microcontroller.

    3. The BH1750 Lux/Light sensor - TBD.

    4. The DFRobot MAX98375 I2S Amplifier module

    This is the back of the audio module, from top-right clockwise:

    1. The blue solid-state 1 Amp fuse.

    2. Adafruit VL53L4CX Time of Flight Sensor - to alert diver if they are too close to the lake/sea-bed.

    3. Lithium rechargeable battery (charged through battery charging circuit in the Beetle ESP32-C3)

    4. Not visible, buried in the middle! The Adafruit Micro SD Card breakout PCB.

  • Components List as of 30 May 2023

    Mark B Jones05/30/2023 at 11:05 0 comments

    I wanted the components list as of today to be listed out in a categorised order. The components project section unfortunately is flat, so hopefully this will present the information in a clearer manner.

    Mechanical Components for the Mercator Origins Sat Nav/Telemetry Console

    Yellow Float box with transparent lid - Underwater Kinetics IP67 Ultrabox 408 (waterproof to 5m), including lanyard. 
    1 x yellow cable/hose strain relief rubber tube (beaver with amalgamating tape or unbranded)
    1 x Nite-Ize S-Biner size #4 or #5 - black or stainless steel
    11 metres x 4-core 4mm sub-sea Blue Robotics Ping Cable SKU: BR-100452
    2 x  Blue Robotics 4.5mm LC Wet Penetrators SKU: WLP-M06-4.5MM-LC-R1-RP (6mm drill bit required, recommend stepped drill for drilling housing, HSS drill for float box)
    2 x 6mm non-shake washers
    Navigation Console: 1 x gopro hero 9/10/11 housing - non-OEM or OEM
    Audio Module: 1 x gopro hero 9/10/11 housing - non-OEM or OEM
    1 x upcycled generic 3D Print spool (diameter: x cm, depth y cm)
    2 x button mounts - 3d print and schematics
    2mm nano/gecko tape - fix housing to spool
    1mm nano/gecko tape - mount internal components

    Float Electronic Components

    1 x USB Power bank - minimum 2500 mAh

    1 x Wifi Hotspot - either a mobile phone or a MiFi-type WiFi hotspot (eg by TP-Link)

    1 x USB A cable.
    1 x USB C plug - breakout with solder pads
    1 x 4-way Micro JST male and female connectors/wire
    2 x 2-way Micro JST male and female connectors/wire

    Clear plastic enclosure box (M5 Stick C Plus Watch box)

    Float computer: M5 Stick C Plus ESP32 microcontroller
    1 x M5Stack MiniGPS/BDS unit AT6558 (Serial UART comms)
    1 x 1 Amp fuse holder and fuse
    1 x RS485 module (5V power, 3.3V signal) (generic board based around MAX485 IC)
    1 x Grove connector female to female 4-core cable - GPS unit to M5 Grove connector
    Silicone wires (multiple colours)
    Future version: 2 x relays and reed switches for contactless rebooting of float and entire system using magnet waved by user over 2 marked locations on the float box.

    GoPro Navigation Housing Electronic Components

    Guidance Computer: 1 x M5 Stick C Plus ESP32 Microcontroller
    Dive Timer Computer: 1 x M5 Stick C Plus ESP32 Microcontroller

    Mechanical push to make switches: 2 x car remote control switches maximum thickness: 2mm
    Non-contact inputs: 2 x potted reed switches
    Leak Detector: 3 x 1M Ohm 0.25w Resistors and 30cm solid core bell wire
    IR interface: 1 x ? Resistor and 1 x ? Phototransistor

    Generic RS485 module (5V power, 3.3V signal) (based on MAX485 IC)
    Adafruit LSM303AGR Accelerometer / Magnetometer - Digital Compass
    Adafruit BME280 Environmental Sensor: Temperature, Relative Humidity and Air pressure sensor:
    Blue Robotics MS5837 Depth Sensor 300 metres max depth
    Future version: Adafruit APDS9960 Proximity, Light, RGB and Gesture Sensor

    Silicone wires (multiple colours)

    Connectors for navigation housing

    2 x 8-way 90 degree PCB header
    2 x 8-way Micro JST male/female connectors
    4 x 2-way Micro JST male/female connectors
    3 x 4-way Micro JST male/female connectors
    3 x Stemma QT/Qwiic 4-way female to female cable connector
    1 x Grove to Stemma QT/Qwiic female to female cable connector

    Audio Module Electronics

    DFRobot Beetle ESP32-C3 (RISC-V Core) Microcontroller
    3.6V 18650 lithium rechargeable battery and holder
    Adafruit micro SD card breakout board
    8GB SDHC Micro SD card
    DFRobot MAX98357 I2S Amplifier module - mono 3W
    Dayton Audio DAE13CT-4 4 ohm/3W coin type 13mm exciter (surface sound transducer)

    future plan: Adafruit BH1750 Light Sensor
    future plan: solid state fuse
    future plan: 2 x potted reed switches
    future plan: : Adafruit VL53L4CX Time of Flight Sensor 1mm to 6000mm

    Audio Module Connectors

    1 x 4 way Micro JST connector male
    2 x 4 way Micro JST connector female
    1 x USB C plug - breakout with solder pads
    Silicone wires (multiple colours)


    2mm and 1mm thickness nano tape

    dual wall heat shrink - sizes: 1mm,2mm,4mm,6mm
    The rubber white putty stuff?
    Hook and Loop fastenings...

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  • Assistive Tech Update: Progress on the Audio module (called Silky) for guiding people with impaired vision.

    Mark B Jones05/22/2023 at 16:08 0 comments

    How is Mercator Origins a piece of Assistive Tech?

    With the end date for the challenge round for the Assistive Tech category of the Hackaday 2023 prize fast approaching (30 May 3pm BST) I wanted to write a log on how the audio module is going.

    With the added Audio Module, Mercator Origins will be able to provide guided assistance through sounds, tones, vibrations and spoken instructions. This is in addition to the usual visual guidance provided today. 

    I was speaking to a doctor who specialises in dive medicine and who also is involved with a charity who teaches and enables disabled people to scuba dive. He told me a story about the bravest person he knows, who has impaired vision. They found the feeling of being weightless (and neutrally buoyant) in the water was one of the most empowering and moving experiences of their life as they could be independent. I would like to think that scuba diving can provoke a feeling of autonomy and empowerment for those who have difficulties with movement or who are challenged by the clutter and busyness of our everyday lives. Using only the breath to control one's attitude (ie angle) and position in the water column is something that I love as a sighted person, so if this can be experienced similarly for people who wouldn't think that this sort of thing is accessible then that would be awesome.

    I am told that a person who has an impaired sense, for example sight or hearing, is quite likely to have a more highly tuned ability (compared to the unimpaired person)  to experience their other, unimpaired, senses. It is for this reason why I believe that empowering impaired-sight and blind people to enjoy the underwater world, one of weightlessness and freedom in 3D space/water, is something which might provide a wonderful experience that is outside their usual day-to-day living. To give hope and joy to a person who has challenges that I cannot begin to fully appreciate due to my sightedness and life long exposure to the world through the wonder of vision is something which I have a tremendous drive for and why I have devoted so much time and effort throughout 2023 to this project.

    Attuned Senses, Inclusion and the Desire to Expand a Person's World Experience

    One or two people have questioned why a sight impaired person would like to visit underwater features in a dive lake or in the sea when they can't see them. I think this is one of the challenges we all have when making the world inclusive for all. It can be hard to imagine or put ourselves in the shoes of those who have a vastly different life experience to ourselves or to the usual day-to-day experience of the majority. 

    I would love a person with impaired sight to be able to visualise in their mind's eye the feature that they are visiting by reaching out and touching the object, feeling the contours and experiencing the textures and embodiment of the structure. In the dive lake at Wraysbury it is perfectly safe to touch all the objects (with gloves, there are some rough and rusty bits!)  and there are no corals or other delicate organisms which can be damaged by a person reaching out and touching their surface. There are plenty of fresh water mussels which are very resilient to us humans and also freshwater American Crayfish which crawl about the lake bed minding their own business. There are fish too, but they are not going to roll over to have their tummy tickled - unlike some Grouper fish I have seen in Turkey,

    I would like Mercator Origins to guide the person around the lake using sounds, feature by feature, whilst they are still accompanied by their dive buddy / instructor who is always there to provide a helping hand and for good dive practice safety. The aim is to provide a unique experience in a safe environment to provide an empowering feeling of autonomy to the person using the Mercator Origins guidance system.

    So there we have it, an audio-enabled Mercator Origins is a piece of tech...

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  • 30th May, 7pm - Scuba Hacker to present in-person and online at Microsoft Reactor, London - join me!

    Mark B Jones05/22/2023 at 09:40 0 comments

    I'm very excited to report that I've just signed up to do a 30 minute presentation on 30th May at Microsoft Reactor,  London (and online :-) ), to talk about my Mercator Origins sat nav project. I'll be covering the journey of discovery, my renewed passion for technology and of course go through the build and test of my invention.

    Anyone with easy access to Central London... I would be thrilled if you came along - I need all the moral support I can muster, it will be my first ever presentation like this!

    Sign-up on meetup or just add to the comments below, including your real name (or contact me directly via WhatsApp, my LinkedIn or email, below) , if you plan to come along and I will advise the organiser, Richard Kirby, of numbers and names.

    Alternatively you can attend online. If you setup a meetup account you should be able to get a link - I'll check with Richard.

    Meetup Event: Raspberry Pint - Raspberry Pi / Microcontroller Making & Nerding

    When:     7PM to 9PM   Tuesday 30th May

    Where:     Microsoft Reactor London 

                     70 Wilson Street 


                     EC2A 2DB United Kingdom

    My linkedin:

    Or email me:

  • Scuba Hacker's Tools and Consumables

    Mark B Jones05/18/2023 at 07:25 0 comments

    These are my soldering tools and consumables. I haven't actually had need to use (1), (2), (6) or (9) but it's nice to have them on hand.

    1. Antistatic wrist strap - protect your ICs / sensor modules.

    2. Solder Flux

    3. Damp Sponge for wetting/wiping solder tip

    4. Tin solder (preferred over lead/tin solder)

    5. Game-Changer: Tinning compound - good for cleaning/wetting tip. Better than sponge, use when the soldering iron seems to stop melting the solder despite being at 360 degrees C.

    6. Solder Sucker

    7. Game-Changer: Solder Braid - heat this up and press to solder blobs to suck away the solder from the joint. I prefer this to the solder sucker for tiny joints.

    8. Game-Changer: Coiled wire for cleaning the solder tip - another way to clean the tip. Cannot have too many ways to maintain your tools!

    9. Anti-static gloves - protect your ICs / sensor modules.

    10. Game-Changer: Temperature controlled soldering iron - use 360 degrees C for soldering with 100% tin solder.

    These are some of my other tools:

    1. Helping Hand - useful for holding wires and components when soldering - literally a third hand.

    2. Game-Changer: small vice - I prefer this to the helping hand. Hold components, sensors and wires for soldering.

    3. Game-Changer: Magnifying Glass with LED - a little beauty! Head mounted. I used to use jeweller's loupes but these I found too difficult to use.

    4. Different lenses for the magnifying glass. From weak to strong.

    5. Game-Changer: A stepped drill, starting at 4mm going up to 22mm - titanium coated. This is the game-changer that allows me to quickly drill 6mm holes for the wet penetrator (cable/bulkhead connector) and 10mm holes for the depth sensor in the GoPro enclosure without excruciating 30 minute youtube videos showing how hard it is to do with regular HSS drill bits.

    6. Magnifying glass - fits onto helping hand. Only use it for quick inspection of solder joints that are close together to make sure they are not shorting.

    7. 16mm spanner/wrench for tightening the pressure sensor nut.

    8. 12mm spanner/wrench for tightening the wet penetrator (cable/bulk head connector) nut.

    9. Wire cutters - only use for normal copper stranded wire (and heatshrink) cutting to keep them sharp.

    10. Game-Changer: DCC Concepts Wire strippers, specifically designed for fine wires. Can also be used for thicker wires.

    And the bigger tools:

    1. Original Black & Decker Workmate - circa 1980. This is an all-steel original Workmate which was my Grandad's, parts are still available! He taught me woodworking skills using this when I was a young lad. My Grandad also introduced me to electronics and soldering at a young age with one of those 101 electronic projects boards which had coiled springs to connect each of the components. Bless him, he passed away in 1992 and I miss him incredibly to this day. I so wish he could have seen this project.

    2. Digital Micrometer - for measuring things accurately.

    3. Dremel (non OEM, don't need Dremel brand) bits.

    4. Dremel high-speed drill - with an extended power cable. You don't need an official Dremel drill, any will do.

    5. Glue gun - hot temperature version.

    6. DeWalt wireless drill with variable speed on trigger and three set selectable maximum set speeds. Any old drill will do.

    These are the consumables I have found useful:

    1. Model Filler - I have used this to help fix USB cable exiting the small plastic box holding the electronics in the float.

    2. Game-Changer - 2mm thickness Nano Tape (or Gecko Tape) used for mounting the GoPro/console enclosure to the spool holding the cable. Easily removable without residue, yet extremely strong in operation.

    3. Game-Changer - 1mm thickness Nano Tape (or Gecko Tape) used for mounting sensors and other small components in both float electronics box and the gopro console/enclosure. Easily removable without residue, yet extremely strong in operation.

    4. Revel Contacta...

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  • More ideas for public consumption...

    Mark B Jones05/16/2023 at 18:59 0 comments

    In the interests of public discourse, here are my future plans for the open source Mercator series of Sat Nav consoles: (this prevents patents from being raised by other parties because this blog demonstrates prior art for future patent applications.)

    Mercator Origins:

    Development status for (1): hardware built for (a) and (b), enclosure ready, software needs writing through integration of a number of existing sets of sample code. haptics may be possible with no-cone speakers used for (a) and (b), the bone conductor transducer is sat in the lab but the questions concerning waterproofing, power and radio are still all on the table.

    1. Underwater audio testing for (a) verbal instructions - turn left, turn right, go ahead. (b) tone diections, (c) haptic/vibration directed guidance, (d) bone conductance transducer for personal audio communication requiring wireless comms between the diver's console and the diver. The intention is to prepare the ground for providing water-borne navigation/guidance assistance to individuals who are partially sighted or blind.

    Development status for (2) : lasers and sensors are in the lab and waiting for breadboard testing. Laser driver circuits and components are also ready for testing. Should be a case of 'just' mounting the lasers and the photo sensors opposite each other in the two enclosures, on either side of the cable spool.

    2. Addition of second GoPro enclosure to the spool (on the opposite to the guidance console) held by the diver which houses the audio/vibration transducers for enabling audio/haptic guidance features. The two gopro enclosures then need to communicate with each other, namely the guidance console needs to direct the audio module to 'speak' left, right or straight ahead using whatever audio comms method is preferred by the diver. The audio console also needs volume up/down buttons enabling, together with stop/start audio directions. Thus a bi-directional comms link is needed between the two enclosures. I do not want to drill holes for a cable between the two enclosures as this will increase risk of leakage and also require an awkward sub 10cm cable joining the two enclosures. My proposal is to use two lasers to communicate across the 10cm or so of water between the two modules, one laser for each 'direction' of communication.

    Mercator Elements

    * Development Status: Complete (capability was required to function in the pressure pot test for Mercator Origins)

    * Standalone console/enclosure using the same code as Mercator Origins, no cable or float required, that can be used for water surface activities such as snorkelling, kayaking, windsurfing, kitesurfing and kayaking. All functionality of Mercator Origins except (1) no depth sensor and (2) only one M5 Stick C Plus in console enclosure because the remaining space needs to be occupied by an onboard battery. Still connects to the internet via wifi and sends telemetry including location - will require user to have their phone in hotspot mode in a waterproof pouch on their person which Mercator Elements will connect to.

    Mercator Discoveries

    * Development Status: Conceptual plans in motion, hardware sourcing in progress.

    * A brand new enclosure/float capable of navigation and live video streaming of the dive to the internet, as well as telemetry upload to the internet.

    Other Areas for Research - Long Term Vision

    * navigation via underwater triangulation using an array of underwater radio or sonar beacons. Avoids need for float and cable, allows for wreck penetration.

    * navigation within underwater caves using short wave radio beacons placed on the surface above the cave system to triangulate location.

  • At last! Following successful sea trials in Gozo, github now has all the code publicly accessible!

    Mark B Jones05/16/2023 at 16:01 0 comments

    ---> Click there for Mercator Origins Code Repos <----

    All code has been developed using the Arduino IDE, hence the monstrously sized INO file for each of the three mercator-origins projects. Lots of tidying up to do, the major one will be moving to VS Code environment which may only happen in June.

    These are the repos: (top three all named after shark species!)


    the code running on the M5 Stick C  Plus is the yellow float at the sea surface that connects to the GPS, connects to the internet via WiFi hotspot and connects the diver console with the sub-sea up/down link.


    The code running on the M5 Stick C Plus in the diver's console gopro enclosure that is running the navigation and guidance software. It also has all sensors (except leak detector) wired into it.


    The clock/uptimer/downtimer shown on the second M5 Stick C Plus in the console go-pro enclosure. Connects to the leak detector only at present.


    My Master's dissertation and code for stock cutting (using a Genetic Algorithm AI engine) that will be adapted later on to be a travelling salesman-type engine that will provide optimised dive planning for many-waypoint journeys.

  • Live track from Xlendi, Gozo in 10 mins!

    Mark B Jones05/15/2023 at 10:06 0 comments

View all 40 project logs

  • 1
    Step 1: Gather components to build the float box (containing ‘Lemon’ M5 Stick C Plus)

    IP67 Float Box, M5 Stick Watch Plastic Case or any suitable project box for the electronics, RS485 PCB and 4-pin JST female connector, GPS PCB and antenna, Voltage Boost Regulator PCB, M5 Stick C Plus, 90 degree 8 x pin header, 5cm Grove cable, 25cm 4-core cable with USB A plug, 1 x USB-C prototyping plug, 2 x Micro JST 2-way sockets (male), 4-core flat cable.

  • 2
    Step 2: Setup a free Qubitro account.

    Setup a free account at, create a new project called ‘mercator-origins’ and create a new device called ‘M5.Lemon’. Click on Overview / Connection Details to get the MQTT server host/port and device username/password and then goto Settings to get the Device_ID and Device_Token. These credentials will be used in step 13.

  • 3
    Step 3: Drill the float box

    Drill using a 6mm bit from the outside of the base of the IP67 float box through to the inside, aiming for the centre of the base of the box. 100mm x 60mm offset.

View all 62 instructions

Enjoy this project?




[this comment has been deleted]

Mark B Jones wrote 05/31/2023 at 07:34 point

Hi, thanks for your comment!

Indeed, I have a Garmin InReach Mini 2 which is a hand held emergency satellite comms transponder (waterproof in the case) which can send and receive text messages and location, including SOS messages to a dedicated Garmin support centre who then coordinates with local rescue services - so if the dive boat leaves you in the ocean which does happen (!) then you have a lifeline. 


There is great potential to provide built-in satellite comms within the float box due to the amount of space available for this plus other edge computing devices. I wouldn't integrate with a Garmin or similar unless there is a device out there which has an API, it would need to be an off the shelf Sat comms module that can connect to one of the LEO (Low Earth Orbit) satellite constellations, eg Iridium. Then there is the question of alerting emergency services, for this I would need to find an existing SaaS service that can do this as it's a safety critical function and there are other human factor considerations to take into account.

There is already support for remote internet comms in the float when out of 4G coverage as long as the dive boat has internet access, eg through a satellite internet router. This is because the float can connect to the boat's WiFi network (instead of the 4G WiFi hotspot, or as well as to provide a backup!) providing a satellite hop as a transparent transport to communicate with emergency services and live-tracking dashboards.

It's exactly this kind of potential which you raise which excites me about this mega project. There are so many possibilities for current and future development. The challenge is capturing all the ideas and then executing on a focussed development plan.

  Are you sure? yes | no

Mark B Jones wrote 04/14/2023 at 23:04 point

A quick update - I went back to Putney pool this evening and had another short dive. This time it wasn't a gps test or 'is it gonna leak' test. Nope - I packed it with a Fast Fourier Transform (not written by me I might add - it's part of the M5 Stick C Plus demo firmware) which uses the mic to record sounds, does  a Fourier analysis and displays that frequency spectrum in real time on the display.

Why do that? I want to see if we can analyse the bubble sounds of breathing out (low frequency) and the regulator high frequency sound when breathing in, to detect and assess the diver's breathing rate.

Well the answer is visually I could see the distinct difference between the in-breath, the pause at the top of the breath in, and the out breath. I reckon we can have some fun analysing this! Nothing was recorded permanently, this is pure research at the moment.

Become a zen diver by being trained in meditative breathing underwater by your dive computer?! Use less air, expend less energy, have a longer dive and be more chilled out at the end of it. What's not to like?!

  Are you sure? yes | no

Mark B Jones wrote 04/14/2023 at 22:56 point

So having a sub-sea comms link back to the surface and to the internet means the divers can also have pre-canned messages available such as 'emergency help needed' which can be sent to the shore lookout who can raise the alarm with the RNLI (Royal National Lifeboat Institute) here in the UK or the coastguard. Shore dives will usually have internet access here in the South East of England. There is always the option of using LoRa Radio as a backup requiring no  mobile network though!

  Are you sure? yes | no

Mark B Jones wrote 04/14/2023 at 22:51 point

Messages will be sent back up to the float because I'd like to get telemetry back from the deep, for example depth, to overlay on the real-time GPS track viewable on the web. Say I'm doing a shore dive with my buddy and I have a third person who is our look-out on the shore keeping an eye on us which is best practice. Then that person could actually have the live track including depth (in version 2.0) on their phone so they can see if the divers are deviating from the dive plan and if they are off course. If there is something obviously wrong they can raise the alarm.

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Mark B Jones wrote 04/14/2023 at 22:47 point

Answering @Brett Smith ... 

GPS messages need to be sent from the GPS module down to the console so that we can calculate the bearing and distance to the next target feature we want to see, for example in Wraysbury dive lake in the UK that could be a sunken plane or a school bus! I want to be able to rock up to the dive centre with my dive buddy, agree on say a 40 minute dive where we want  to see features x, y, z, a, b and c and have the console guide us round the lake and correct us for deviations from course. It can also time us and tell us if we need to hurry up to get back to the jetty on time or whether we can chill out and slow down to watch the fish (or actually at Wraysbury it's American Crayfish mostly).

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Dan Maloney wrote 04/14/2023 at 21:16 point

Interesting -- something like this would reduce those stories about divers being stranded when the dive boat takes off without them. Looking forward to more detail.

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Brett Smith wrote 04/14/2023 at 16:00 point

Super cool! Love the re-use of the gopro case! How is this going to work, is this an underwater radio project?

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Mark B Jones wrote 04/14/2023 at 16:54 point

Hi @Brett Smith 

Thanks for your question and congrats on being my first commenter on this project and also the first commenter on my hackaday account! 

My approach is to be super detailed so here's a taste of how in-depth I'm going to be throughout documenting this project:

GPS signals can't travel under water so I am using a tethered float box (IP67 rated) holding the GPS at the surface together with sub-sea specification UAV/ROV cable with matched connectors for a waterproof seal both at the float and at the gopro case ends.

Here in the UK it's a requirement for all diving in the sea to use Surface Marker Buoys. These tell boaters and your dive boat skipper where you are located so that (a) boats don't go over the top of you and (b) the skipper doesn't lose you on a drift dive. SMBs are normally on a long string connected to a reel or spool held by the diver whilst diving. The difference here is that the spool is much bigger than normal - in fact it's a reused 3d printer spool that I acquired off ebay for £1 ! And instead of string (which is a tangle hazard anyway) we're using 4mm 4-core PVC cable that is reinforced and designed for high shear and strain resilience/strength whilst also being almost neutrally buoyant (ie weightless) underwater.

The gopro case is rated to 60m which is way beyond my dive capability, my maximum dive depth is 40m. I am a PADI Master Scuba diver and have the SSI Deep Diving speciality (Recreational) which is where my 40m limit comes from. I actually prefer to restrict my dives to 30m because the deeper you go the darker it gets and the more colours are washed out due to light refraction. You also get much less time underwater at that depth because of what we call decompression limits, ie you don't want to get the bends so you have to restrict your time at depth, and also air gets used up much faster at 40m than say at 30m - all in all there is a greater safety margin and I am very cool with that.

Version 1 of this project is using an 11 metre cable because that's how deep my local dive lake is!

Version 2 will use a minimum cable length of 30m.

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Brett Smith wrote 04/14/2023 at 21:26 point

Hey thats brilliant! People are so afraid to test/post their DIY dive projects, its really cool to see stuff like this. Just a couple questions, why does the cable to the surface need to carry a signal? Are you sending messages? Why not just make it broadcast once it gets to the surface?

And then what radio protocol are you using to communicate with the boat captian once the SMB is launched?

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