What is Flat Island, and what are its notable features?

Detailed answer

Flat Island, Popoia in Hawaiian, is a low 3.67 acre islet off Kailua Beach and Lanikai, managed by DLNR DOFAW as a State Seabird Sanctuary used mainly by wedge-tailed shearwaters (ʻuaʻu kani) and Bulwer's petrels. Visitors may land without a permit but must stay below the high water mark, and the islet is closed from sunset to sunrise, with no dogs, fires or camping. It is a popular kayak and paddleboard trip; go in the morning before the trade winds build. It is often confused with Mokuʻauia (Goat Island), which lies off Lāʻie farther up the windward coast.