Underwater photography or marine photography is the process of taking photos while under water. It usually is accompanied by the use of scuba diving gear, but can also be achieved through snorkelling, swimming, using submersibles, or even using automated cameras lowered from the surface. The process allows for great photographic opportunities such as fish, marine mammals, shipwrecks, cave systems, geological features and underwater landscapes to say the least.
In order to achieve successful underwater photography, specialised equipment and techniques are required. The equipment needed can be cameras specifically made for underwater photography as well as modern waterproof digital cameras. The first amphibious camera was the Calypso a 35mm film camera conceived by marine explorer Jacques-Yves Cousteau (1910-1997) designed by Jean de Wouters and manufactured by Atoms in France by 1960. The camera allowed for for it to be used 60 meters below sea level. Underwater photography however goes back as far as 1856 when William Thompson took the an underwater photograph by using a camera mounted on a pole.
Some cameras that are intended for out of water use can be used underwater using protective housings. Most housings are specific to each camera allowing for the user full access to camera settings and use of lens of their choice. There are some issues when using watertight housings, refraction. Refraction causes the image to become distorted through the glass port, the solution for this is to use dome shaped or fish eye port which helps correct the distortion when using wide angle lenses. Most manufactures make these domes part of their housings. With macro lenses in the other hand the distortion caused by refraction is not a problem and can actually benefit macro photography as refraction increases the magnification on a macro lens.
Under water photographers generally use wide-angled lenses or macro lenses, both allowing close focus. This allows for a shorter distance of water between camera and subject, as having too much water between the camera and the subject reduces clarity due to light scattering.
One of the most difficult aspects of underwater photography is the use of a flash or strobe. They should be used to supplement the exposure and restore lost color in combination of a primary light source. By using a combination of both light sources the photographer tries to achieve a balance between them. However deeper and darker areas become harder to photograph. Colour is also absorbed as light travels through water so the deeper you are, the less colour remains making a strobe or flash essential to replace the lost colour contrast and texture.