You will need an underwater camera housing to keep your valuable camera dry. This is a very important piece of equipment.
When shopping for underwater camera housings, you may choose from single lens reflex (SLR) housings and digital housings. As a general rule, most underwater housings for compact digital cameras use externally mounted wide-angle lenses. These lenses are actually quite good for their low price and offer 100 degree wide-angle coverage and macro down to 1:1 (life-size) reproduction. Since these cameras have built-in zoom lenses, they are quite flexible and can be used for a large variety of subjects. Most of these lenses can be added or removed while underwater and therefore allow you to be ready for anything.
Check your underwater camera housing to see how many feet it is rated (its maximum working depth underwater). Will the camera be adequately and safely protected during use in rugged environments? Does it have injection-molded plastic? Is it constructed to take the rigorous environments that underwater photographers and outdoor photographer's experience, and will it protect digital cameras in these demanding activities?
Just as most underwater video manufacturers limit their design efforts to Sony cameras, the majority of still housing systems are built around the Nikon line. Although Canon has increased in popularity with topside professionals, few underwater housings are offered for Canon systems.
For your underwater camera housing, you will want something durable. It should be made from machined aluminum, black type III 'hard' anodize finish, and sealed with a nickel-acetate process, have no sticking buttons or faulty electronic controls, use quality optics with clarity, sharpness and no vignetting (cutoff dark corners) to spoil your images. It should allow you to change lenses underwater from wide to macro with a MultiPort and include lighting options.
Underwater Cameras Info provides detailed information on underwater cameras, including underwater digital cameras, underwater video cameras, and underwater fishing cameras, as well as underwater camera housing and cases. Underwater Cameras Info is the sister site of Disposable Cameras Web.