There are 6 ways to overcome light loss when taking pictures underwater.

1. The use of natural light (the Sun).

Between 10am and 2pm the sun should be directly over head. The surface water condition is also important, if the water is calm less sunlight is reflected away but if the surface is rough especially after a storm a lot of sunlight will be reflected away and it will be darker under the water.

2. A Strobe.

This is one of the best overall solutions in low light. One of the great advantages of using a strobe with a digital camera compared to a flash system is that you get the chance to see in the view finder what the picture you are about to take will actually look like.

3. Use high speed film.

High speed film has more sensitivity and requires relatively less light than slower film.

4. Stay shallow.

The deeper you go the less light, so  if you don’t have artificial light by staying shallow you can still take picture without major colour loss.

5. Get closer to your subject

The less water distance between you and your subject the less light is absorbed as it travels between your subject and your camera.

6. Flash