The Site comprises two coral atolls located 50km apart in the Tasman Sea which are the southernmost open ocean platform reefs in the word. Their coral structures, which stand on isolated, oceanic sea mounts, are influenced by both tropical and temperate ocean currents. They support a diverse marine fauna, including seven heretofore undescribed fish and three endemic mollusc species, and are the only known habitat for these species in a vast area of ocean. To date, at least 195 fish species from 36 families have been recorded at the Site. The reefs are a stronghold for predatory fish and sharks, including black cod (Epinephelus daemelii) and Galapagos reef sharks (Carcharhinus galapagensis). A large number of shipwrecks in the Site also give the area considerable marine archaeological significance.