Marine iguana
the amazing marine iguana (Amblyrhynchus cristatus) is an iguana found only on the Galapagos Islands. It is the only modern lizard, to live and forage in the sea. Also unusually, it is a vegetarian. It only eats algae.
The iguana can dive over into the water. It has spread to all the islands in the archipelago, and is sometimes called the Galapagos marine iguana. It mainly lives on the rocky Galapagos shore to warm from the comparably cold water. It can also be spotted in marshes and mangrove beaches. Charles Darwin described them:
"The black Lava rocks on the beach are frequented by large (2-3 ft [60-90 cm]), disgusting clumsy Lizards. They are as black as the porous rocks over which they crawl & seek their prey from the Sea. I call them 'imps of darkness'. They assuredly well become the land they inhabit".
References
Iguania
Reptiles of South America