Maro Reef

Other names: Ko'anako'a

Geography: A complex of reefs running northwest to southeast.

Distance from Honolulu: 850 miles

Highest point: awash

Type of island: Reef region

Acreage dry land: 1 acre, sometimes

Coral reef within 13.8 miles: 316,812 acres

History: Discovered in 1820 by the crew of the ship Maro. Ships tend to avoid it because of the danger of being wrecked, and scientists have had problems trying to study it because it is so difficult to get to and through the reef.

Biology notes: Maro, the largest coral reef in the Northwestern Hawaiian Islands, has more kinds of coral than any other of the chain's reefs and islands. Scientists in 2000 and 2001 counted 37 species of stony corals here.