According to Marine Bio, 18th century British Captain James Cook, who mapped uncharted waters and documented marine life, is considered the first modern marine biologist. Cook's studies led to further marine life studies by scientists, such as Charles Darwin.
There have been many famous marine biologists besides Cook and Darwin. Aristotle is considered the first person to have written anything concerning marine life and science. Rachel Carson, a former marine biologist for the U.S. Fish and Wildlife Service, was famous for translating her scientific findings into popular literary writings that promoted a sense of awe in respect to nature. Carson lobbied later in life about the negative effects of pesticides.