The Raspberry Pi-Powered Sensea Delivers Color Imagery and Temperature Readings From Under the Waves
Simple deploy-and-wait logger captures photos with timestamps and temperature readings for later analysis on dry land.
Pseudonymous educator and maker "Unboxed_STEM," hereafter simply "Unboxed," has shared a design for a low-cost Raspberry Pi-powered underwater gadget designed for sub-surface videography and temperature monitoring: Sensea.
"We talk a lot about protecting oceans and rivers — but how do we actually measure what's going on below the surface," Unboxed rhetoricizes by way of introduction to the project. "Sensea is a DIY underwater explorer built with a Raspberry Pi, camera, and simple modular sensors that brings citizen science within reach of any STEM [Science, Technology, Engineering, and Math] club or classroom. It captures underwater video and logs time-stamped water temperature data — even in remote locations without internet access."
The Sensea is built around a low-cost Raspberry Pi 3 Model B+, a few generations behind the current Raspberry Pi 5 but easily powerful enough for the task at hand. For sensors, it's connected to a Raspberry Pi Camera Module 3 and an Analog Devices DS18B20, plus a DS3231 real-time clock (RTC) module for tracking the time. Power comes courtesy of an off-the-shelf USB battery pack — another reason for picking the Raspberry Pi 3 over the more power-hungry Raspberry Pi 5.
The body of the device — which doesn't quite meet the requirements to be called a remote-operated submersible, as it lacks any form of propulsion — is built from a 3D-printed electronics bay sealed into an acrylic tube and surrounded by a roll-cage built from low-cost PVC piping. Deployment is as simple as plonking it into the water and allowing it to slowly sink; retrieval is handled by a rope that you hopefully didn't forget to tie to the cage before deploying the device.
"To validate the system, Sensea was deployed in a local freshwater pond under daylight conditions," Unboxed says of the testing phase of the project. "The relatively clear water allowed visible underwater detail to be captured while the temperature sensor logged real-time environmental data. The system was lowered gently into the pond and allowed to operate autonomously, recording 10-second video clips and time-stamped temperature measurements. Together, data collected by Sensea platforms in ponds and rivers across the country builds a picture of local water health that would otherwise be invisible."
Full details and source code are available on Instructables, though at the time of writing a promised 3D print file for the electronics housing had not yet been uploaded.