I tried to do the manta dive, but they were full. The same boat did have a snorkel spot open, which I grabbed up. Basically you hang on to the side of a surfboard sized float with lights in the middle pointed down. The divers are on kneeling on the bottom with their lights pointed up. The mantas get just as close to the snorkelers as the divers. I think it would be a little more cool to be on the bottom, but not that much. Up to you.