Build yourself an inexpensive underwater video camera housing in about 2 hours with simple tools most home shops have. The housing is excellent for snorkeling, kayak, and other surface adventures. I'm not certain of its design for deeper adventures.
Start here https://www.instructables.com/id/Underwater-Housing-for-miniDV/
Those instructions give you the basics and sources for the materials. My design differs a bit in that I use simple bolts rather than spring latches. This was because I needed this in a day and couldn't wait for the latches.
Step 1: Build the "lens" Housing
My version is based on a 4-inch PVC design. Start with a 4-inch straight connector. Trace the interior circlu on the Acrylic. Cut the circle using a jig saw and drum sander to take it right to the line.
Use 5-minute epoxy to glue it in. Tape off anywhere epoxy should not go including the face of the lens. Lay a bead of epoxy right in front of the flat side of the interior flange. Press the Acrylic into it. Lay another thing bead around the face.
Peel the tape while the epoxy is wet.
Step 2: Cut the Pipe to Length
Cut a piece of pipe a bit longer than your camera. A chop saw worked well for me creating a flat end better than the factory end.
Clean the pipe.
Step 3: Build the Template for the Acrylic Ring and Back Plate
You need to design the plates. I built a template on the computer, printed it, and double stick taped it to a piece of plywood. I will try to upload those templates. You can simply draw out a design on the plywood too.
The back plate and ring have the exact same outer design. The ring simply has the hole cut out of the center for the PVC pipe to fit through. Buld however many bolt holes you like.
Use a drill and jig saw to cut the rough shape out. Use a drum sander to get right to the line. Drill the 1/4" holes in the template. The template is now finiished.
Step 4: Build the Acrylic Back Plate and Ring
Cut out the 1/2 inch thick acrylic with a jig saw slightly larger than the template. Center the template and drill one hole into the acrylic. Do not press too hard or you will break out the far side.
Place a 1/4 inch dowel in the hole aligning the two pieces. Drill the next hole and dowel it to align it. Then drill and dowel the final hole.
Use a router with a flush trim bit to trim off the excess. For the photo I removed the paper backing. It is best to leave the backing in place, or replace it with masking tape. This will keep the acrylic from scratching.
Step 5: Assemble the Body
Take the PVC lens assembly from step 1 and use the chop saw to cut off the front 1 inch, just in front of the epoxy bead. This I will call the PVC ring.
Place the acrylic ring and the pvc ring on the pipe. The PVC ring placement is critical. It must be below the rim of the pipe less than the 1/4 inch o-ring thickness so that the o-ring has room to compress. 3/16" is not a bad distance. Mark and PVC cement the ring in place.
PVC cement the front lens assembly on. Just press it all the way on and turn it a bit to seat it right.
If you forgot to put the acrylic ring on, return to step 1.
Step 6: Build the Inner Plate
You are almost done.
Test fit your camera inside the housing. Press it up against the top and sight under it. Build a plate that is wide enough to push the camera against the top a bit. This will help stabilize it.
Glue small strips on either side of the plate inside the housing to keep it from rotating.
Locate and drill a 1/4" hole under the tripod mount hole. Cut a 1/4x20 bolt to length and put a nut on it to hold the plate to the camera.
Slide the assembl into the camera.
Step 7: Mounting
For bolts, use 1/4 inch with wing nuts. Stainless is best. Be sure to use good solid washers on either end to help keep the acrylic from cracking. Do not overtighten. All you want to do is compress the o-ring slightly.
For my purpose, I am mounting the camera to a boat. A hose clamp around a board gives me the clamping surface for my temporary installation.
There have been suggestions about magnetically operating the start/stop button. But for now I operate the camera by starting it up and letting it run. I can edit the footage later. Sound is heavily muffles as you would expect.