Maui, volcanic island, Maui county, Hawaii, U.S. It is separated from Molokai by the Pailolo Channel, from Hawaii by the Alenuihaha Channel, and from the small islands of Lanai and Kahoolawe (both to the west) by the Auau and Alalakeiki channels, respectively. With an area of 728 square miles (1,886 square km), the island is the second largest of the Hawaiian chain (after Hawaii island); it is also the second youngest of the Hawaiian Islands.