Marine iguanas live on the Galapagos Islands. Like most reptiles, they often bask in the sun to warm up. Once they are sufficiently warm, they dive into the water and go looking for food. Marine iguanas graze on the algae on rocks on the seabed. They often can't do this for more than an hour or so because the water is cold. Then they come back up and find a spot on the warm rocks.