There are two types of underwater cameras: cameras specially made for underwater use, and land cameras with housing. High-quality film cameras directly intended for underwater use are no longer available on the markets for new devices. Since high-quality digital cameras were never specially made for underwater use, the most common option is to take a normal digital camera under water in specially designed housing. Compared to a land camera in housing, genuine underwater cameras have an advantage in terms of usability and higher optical quality of their underwater wide-angle lenses. The optical quality difference lies in the fact that a curved dome port must be used in front of a normal wide-angle lens. This has a softening effect at the fringes of the image field, which is clearly more extensive than for underwater wide-angle lenses. The quality difference is most emphasised when shooting with large apertures. However, land cameras in housing offer a very broad range of optical options and accessories. This gives them greater versatility and flexibility than genuine underwater cameras. In addition, the difference in quality of digital cameras usually surpasses film camera quality.

Even in ideal conditions, vision is limited underwater. The photographer tries to get as close to the subject as possible, in order to minimise the water mass and particles in the space between. Roughly speaking, underwater photography divides into two sub-areas: underwater landscape photography using very wide-angle optics, and close-ups using macro or micro optics. Medium focal lengths and narrow wide-angles are difficult to use underwater because landscapes must be shot from too great a distance, and the photographer is unable to focus close enough. In such cases, too great a distance remains between the lens and subject, with the accompanying large water mass and number of particles. Additionally, flashes lack the power to bring the subject's colours to life. The result is a drab, undynamic and dead picture. However, in certain situations, medium focal lengths and narrow wide-angles come into their own, for example when photographing sharks.