here is a sample of manta ray in 3d!
shot in new caledonia. The weather was good, but the water was very murky.
This demonstrate the difficulty of shooting in 3d, even in ambiant light with no flash. The water have to be perfectly clear, if not 3d camera will focus on everything, including the backscatters.
Normally in 2d shots, when the water is murky, you can try to come closer, or shoot macro. Not in 3d, and not with mantas! The water have to be perfectly clear.