Huilua Fishpond

Huilua Fishpond, in Ahupuaʻa O Kahana State Park on windward Oʻahu, is one of the few surviving ancient Hawaiian fishponds that were still operational well into the 20th century. It was declared a U.S. National Historic Landmark in 1962, shortly after it had been severely damaged by the 1960 tsunami.

Source: Wikipedia