The introduction of underwater digital cameras has made it possible for divers and under water enthusiasts to practice the art of photography in oceans, seas and pretty much everywhere underwater. They are also designed to protect the internals of the camera in situations where the camera might be splashed or submerged shortly, like on a boating trip. Several manufacturers build cameras purposefully designed for underwater use, while others build shells that work with existing models, not purposely built for underwater excursions. If you do not need the professional features of a more advanced camera or have reservations against using an expensive camera for your underwater shots, you can always purchase a disposable type unit; although these cameras have softer lenses and lower sensor resolutions, which might degrade the overall quality of your photos.
The Optio W60 digital point and shoot camera by Pentax is a waterproof model. Pentax has been producing waterproof cameras for a while. This particular model sells for about $300 but can be found for less if you search around. It sports a 5x optical zoom lens that starts at 28mm wide angle with a 10 mega pixel sensor. The W60 can be used up to a maximum depth of 13 feet underwater for 2 hours. It has a convenient 2.5 inch LCD which is great for underwater use with out having to rely on a miniature viewfinder.
A more rugged designed underwater camera is the Olympus Stylus Tough 8000. Like the name implies, it certainly is tough, as it is shock proof from a drop of 6.6 feet and can be used up to a maximum depth of 30 feet underwater. Beyond this depth visibility for a photograph may be very limited anyhow, so you could say that this camera is very high spec.
Canon didn't get left behind in this specialist market, unveiling their Powershot D10 for under water photography enthusiasts and hobbyists alike. Canon made their D10 not only water proof, but crash proof and freeze proof as well. The D10 will survive a "swim" to a depth of 33 feet, can be dropped from 4 feet, and can be subjected to a temperature of -10C. This little camera would not even register the abuse. The D10 has a maximum resolution of 12 megapixels with a bright 2.3 inch LCD display for easy viewing. The Powershot D10 will set you back about $320.