This image of a green and pink coral reef was captured by NOAA photographers off the coast of Swains Island in American Samoa in the Pacific Ocean. Swains Island is an atoll in the Tokelau chain. It is a ring of coral that formed around an extinct volcano. The volcano eventually eroded away, leaving only a ring of coral. American Samoa is a string of seven little islands in the South Pacific, 2,500 miles south of Hawaii. The waters around the islands are home to over 115 square miles of coral reefs. These reefs are home to roughly 2,700 known marine species.