Capturing images under water requires certain equipment. We'll start this discussion with your camera choices.
Your first camera decision is the much-debated topic of whether you should choose film or digital. Photographers using a film camera have two main choices: print film and slide film. Print film produce negatives, which are transferred into prints. Slide film, on the other hand, either can be turned into prints or shown through a slide projector. Slides, despite requiring more precise exposure settings, show the brilliant color of the ocean with a projector and have traditionally been what most publishers use for their work. Negative film allows photographers to be more lenient in setting the exposure, but it's more difficult to catalog than slides [source: Frink].
Digital cameras, however, are becoming increasingly popular with underwater photographers. Digital provides instant feedback and the ability to delete images on the spot, which means you probably won't run out of film when the perfect shot swims by. They also have a large depth of field (the part of a photo's subject that's in sharp focus), great zoom range and compact size. However, digital cameras tend to experience shutter delay, take a while to turn on and produce prints that are limited in size [source: White].
Now that you're thinking about whether film or digital is the way to go, you also need to think about how much you're willing to invest. Inexpensive point-and-shoot cameras that you can pick up at the drugstore won't get you top results, but they're ideal for people on a budget. If you're looking for more than a quick experiment, but still need to watch your budget, mid-range digital cameras are a good place to start. For anyone getting really serious about underwater photography, a single-lens reflex (SLR) or digital single-lens reflex (DSLR) camera will give you manual control of your photos and the ability to manipulate your outcomes with different lenses and flash options [source: Dawson].
With your first major equipment decision out of the way, you can now start thinking about protecting your investment from the water. Do a quick underwater kick to the next section to learn about the rest of your basic equipment needs.