If you've got a decent camera in your phone, the waterproof cases are honestly quite good and inexpensive. My sister's got one for her iPhone that we used all over the ocean and freshwater diving in Mexico that would hold up more than well enough for your purposes.
Unfortunately, the camera on my phone is so so at best. And, I want something with a 1/4-20 mount so I dont have to get my hands wet.
I think a GoPro type camera will work well as long as the maker specifically says that is can go underwater.