Underwater Silhouettes

A sihouette is a view of an object or scene that shows and outline and a featureless interior. Silhouettes typically lack colorful detail and the subject is often captured as a dark blue or black outline against the surface of the rippled water highlighted by the light of the sun.

You can use sihouettes to convey the dream like qualities of being underwater. Underwater photgraphers usually try to photograph larger objects in silhouette, such as divers, sharks, mantas, and large corals.

Because you are just dealing with outlines and dark objects you must pay particular attention to the composition of your picture and the position of the subject of your picture. You must make sure that your subject is directly between the your camera and the sun.
Silhouettes are more dramatic and work best when the photographer is diving in clear water with decent visibility.

Depending on the mood you want to create it is best to get close to your subject so that your picture does not end up having a tiny undescernable subject in the middle with a huge dark area around it. Of course there are exceptions to this. For example, in the image on the left I deliberately wanted to convey the sense of space around the snorkler.
The choice of film is pretty arbitrary because you are typically only dealing with a monochrome image, and this is usually blue or green depending on the waters you are shooting in. I tend to stick with Fuji Velvia because I love the color balance of this film.

Another important consideration is your exposure setting. The Nikonos V has a built in light meter but this can give innacurate readings ( and lead to very dark or very light backgrounds) so you might want to bracket your shots (take three pictures varying the exposure up and down one stop) to give a range of effects.

Usually when you photograph underwater you always use your flash but when taking a silhouette picture you need to turn your flash off. In this way, you won't get any back scatter from particles in the water. You can even shoot in somewhat murky water where other shots are impossible.