I did this about a year ago, but I haven’t written about it, so I thought I’d share a little project my brother and I did. Our family was on vacation at Rainbow River, which is a spring in Florida with crystal clear water that stays 73 degrees all year. I’ve SCUBA dived there a couple times and snorkeled many times, and it’s great spot. My brother and I have used it as a platform for testing projects before (like a fish trap we built) and on our most recent trip, we had new cameras we had just bought. They shoot video in 1080p, so we wanted to take some underwater footage. Turns out that the official underwater enclosure for our cameras costs about $300. Instead, we used a clear waterproof box like this:
The one we used was actually a little bigger than that, but I couldn’t find a picture of the exact one we used. Anyway, we stuffed it with paper towels to absorb any water leaks that might form and to position the camera in the right spot. After several tests where we took it to the bottom of the river with no camera in it, we were confident that it would work. It ended up working even better than we expected, and here’s some video we took: (underwater footage starts at about 1:10, before that is us cooking some of the tiny little fish we caught for fun)
One thing I recommend doing is adding ballast. Either a dive weight or some rocks or steel shot or something because trying to hold the thing underwater takes effort, and makes the shot kinda shaky as you’re fighting buoyancy. Ideally, you want it neutrally buoyant, but slightly negatively buoyant is good too.