I can't speak to how watertight the case is. I'm afraid to try it.
I could barely get the camera into the case. The camera binds to the soft plastic sides of the pouch.
Once it's in, don't plan on removing it. It's too tight and no provision was made for camera removal.
There's a nub inside the case that fits into the threaded hole on the back of the camera. That nub goes into the hole, but there's no mechanism to remove it. I had to attach a mounting clip to the pouch and twist hard to get the nub out.
Once you've gotten past the nub problem, the story isn't over.
In order to get the camera out of the case you either get to push on the lens or remove the closure system and peel back the case. It's really bad. The mount for the removable cover scratched the camera body. I was very tempted to cut the case to remove the camera.
After all the stretching and twisting I had to do to recover my camera, I cannot trust that this case has remained water tight. If there were an alternative case, I'd return this one. As it is, I might modify it to use as a splash guard, but that's it.
If you want to work in really wet environments, you'll have to buy the newer model Drift camera that has a hard case.