The small vaquita (Phocoena sinus), a type of porpoise, usually only reaches lengths of 5 feet (1.5 meters). They are only found in the Northern part of the Gulf of California off the coast of Mexico, and their population size is estimated to be less than 600 animals. This makes them the most endangered of the marine mammals. But estimating their numbers is a difficult task considering their elusive nature—vaquitas (spanish for "little cow") move toward the surface of the water very slowly where they take a quick breate and barely disturb the surface. Their dorsal fin is taller than most porpoises and more triangular.