While we were there, we went on a night dive with the manta rays. It was one of the craziest experiences I (Jennifer) have ever had. We went down to the bottom in full darkness and knelt in a circle with our flashlights pointed towards the surface. The light attracts plankton and the plankton attract the rays. This picture is from a book - during our dive, it was much darker, and the rays were much closer (we were cautioned beforehand not to touch them). The ones we saw were about 7-10 feet across.

(See the full-size picture)