Papah?naumoku?kea National Marine Sanctuary consists of approximately 582,570 square miles of marine habitat, co-extensive with the marine portions of Papah?naumoku?kea Marine National Monument. The sanctuary comprises several interconnected ecosystems, such as coral islands surrounded by shallow reefs, low-light mesophotic reefs with extensive algal beds, open ocean waters connected to the greater North Pacific Ocean, deep-water habitats such as abyssal plains 16,400 feet below sea level, and deep reef habitat characterized by seamounts, banks, and shoals.