Sun, swimming, and survival — Except for when it dons full breeding dress, the marine iguana is mostly black, which enables it to absorb heat quickly. Marine iguanas spend a lot of time basking on the rocks, absorbing the heat of the tropical sun before diving underwater to feed. This habit enables them to survive repeated plunges into the cold waters, since reptiles do not have the ability to regulate their body temperature. Sunbathing may be bad for people, but it's a lifesaver for these guys!