The marine iguana, also known as the sea iguana or saltwater iguana, is a unique species found only in the Galapagos Islands. It is the only lizard in the world that forages in the sea, feeding almost exclusively on algae. Large males dive into the ocean to reach algae, while smaller males and females feed in the intertidal zone during low tide. They primarily inhabit rocky shores where they bask after exposure to the cold water, but they can also be found in marshes, mangroves, and on beaches. Marine iguanas are endemic to the Galapagos Archipelago and consist of eleven similar subspecies, each found on different islands. The largest are from Isabela and Fernandina. For most of the year, adult marine iguanas are black, but during the mating season, males change color, with variations depending on the subspecies. Near Española and Floreana, males become bright green and red, while on Santa Cruz, they turn red and black, and on Fernandina, they exhibit a dull green and brick-red coloration. Juveniles are generally black with a lighter dorsal stripe. Although marine iguanas are not agile on land, they are excellent swimmers. They move gracefully through the water, feeding on algae. Larger iguanas venture farther out to sea, using their strong claws to hold onto rocks in strong currents, while smaller ones remain near rock pools. Due to their diet's high salt content, they expel excess salt through their noses, often forming salt crystals on their snouts.