Pinak, Vihaan, and Yuvan are three friends between 10 and 13 years old who spend their weekends testing river and pond water with a homemade underwater camera. Their build, called Sensea, seals a Raspberry Pi 3 Model B+ inside a 10.5cm acrylic tube and cost the team about £130 in parts, cheaper than most consumer action cameras.
What they actually built
Sensea pairs the Pi 3 with a Raspberry Pi Camera Module 3 and a DS18B20 waterproof temperature probe wired over 1-Wire, with a 4.7kΩ pull-up resistor on the data line to keep readings stable. A PCF8523 real-time clock module timestamps every reading even with zero internet connection, which matters when your test site is a riverbank. A Python script called sensea_logger.py triggers 10-second video clips and writes temperature data straight to the microSD card for retrieval after each dive. Power runs off a plain 5V USB pack, so there's no custom battery board to solder.
The team chose a fixed manual focus over autofocus, since suspended particles in river water tend to confuse autofocus systems and blur the footage. One end of the acrylic tube is sealed permanently with a marine-epoxy bonded disc and a waterproof cable gland for the sensor cable. The other end uses a plumber's expanding drain plug so the team can reopen it to swap batteries. A 2kg dumbbell strapped to the housing sinks the whole rig without needing propellers or thrusters.
The parts and cost reality
- Raspberry Pi 3 Model B+ and Camera Module 3
- DS18B20 waterproof temperature sensor plus a 4.7kΩ pull-up resistor
- PCF8523 RTC module for offline timestamps
- Acrylic tube, marine epoxy, and a cable gland for the sensor wire
- 2kg dumbbell for ballast
Total spend landed near £130. The hardest part wasn't the Python code, it was passing a five-minute bucket leak test before every single deployment.
Spend your Sunday on this
If your robotics club, thesis group, or STEM class wants a weekend project that covers sensor wiring, waterproofing, and Python data logging in one build, this is a solid template to copy. Read the full parts list and wiring notes on Instructables before ordering the acrylic tube, and swap the DS18B20 for a pH probe if your local creek needs a different kind of monitoring instead of temperature.
Originally published on blog.circuit.rocks.
