Uh, check out the Darwin region of Australia for weather, especially rainfall. I'm just guessing, but I would think they spend an awful lot of time under water during their tropical rains.
Almost 68 inches annually, with almost 10 inches in December, 17 inches in January, and 14 inches in February; and it rains 111 days out of 365, most of the rain is in their Spring through Summer. With that much rain, my guess is they spend an awful lot of time "underwater" - when they are in their active growth period.