The community of makers on the Raspberry Pi hardware and variations is EXCEPTIONAL. I easily found example code that worked out of the box. This made early prototyping super easy and successful. Essentially (2) Amazon purchases and a basic teperature probe talking over WiFi was accomplished in less than 24 hours.
I wanted to measure current usage so I purchased a cheep USB multimeter. It worked, but was absolute trash so I eventually upgraded. I also needed a way to try out various temperature sensor configurations so I bought a basic breakout board. I then knew I needed to start experimenting with batteries so I purchased a UPS "HAT" for the Pico that takes an 18650. It worked, but I would later learn that I needed more flexibility.
Looking ahead before I was even done, I knew I would need some kind of waterproof box to put the electronics in, so again back to Amazon and just picking one to try. It worked just fine and allowed me to mock up and experience the frustration of figuring out the optimal mounting positions. This was attempt number two after realizing I had made it so I couldn't plug in the USB ports for power after my first attempt!
I have the box and the temperature probe on a Cat6 cable....might as well throw it outside and see what happens. It ran for about 8 hours before bugs in my WiFi code killed the transmissions. But it lived outside in below freezing temperatures fora little while.
At this point everything seems to be working so I needed to focus on power consumption. There was no way that a battery was going to be able to deal with the constant ~60mAh of draw for any reasonable amount of time. This took the longest for me to crack. The Pico W (original) and the latest version of MicroPython (1.24+) do not play nice together when using the built in sleep and deepsleep functions. They are simply broken. So I did more research and found someone who had written their own sleep function with power management and it worked like a charm! Power consumption now down around 7mAh with the USB enabled!
I placed a call out on the Midwest Underwater Explorers Facebook page for a 3D/CAD designer with printing tools and several hands came up. Josh Caroon started messaging me and after a couple back and forths he came up with this prototype buoy design. The key pieces are the ability to remove the top to get to the electronics box, but also stable in the water. I think it looks great!