When we say "waterproof camera" we can mean a number of things, so it's important to define our terms. There are two main popular types of waterproof camera: waterproof compacts and action cameras. Waterproof compacts tend to resemble an ordinary compact camera, with the main difference being that they're, well, waterproof. They tend to be marked out by distinctive bright colouring (useful if you drop them underwater), and the main edge they have over action cameras is the option of an optical zoom lens, allowing you to get closer to your subjects without suffering loss of picture quality.
Before you start digging into the reviews, a few notes on choosing a cam that's right for you. You'll definitely want to consider frame rate, expressed as frames per second (fps). Some action cameras offer up to 240fps recording, while others only go to 30fps. For standard playback, 30fps is perfectly fine. It's when you want to slow footage down in editing to create dramatic scenes that frame rate matters. Footage captured at 240fps can be slowed down and played back smoothly at one-quarter speed. You may also want to go for a cinematic look, in which case you'll want one that has a 24fps capture option, the same speed used by most Hollywood productions.