The Papahānaumokuākea Marine National Monument is a World Heritage listed U.S. National Monument encompassing 583,000 square miles (1,510,000 km2) of ocean waters, including ten islands and atolls of the Northwestern Hawaiian Islands.

Created in June 2006 with 140,000 square miles (360,000 km2), it was expanded in August 2016 by moving its border to the limit of the exclusive economic zone, making it one of the world's largest protected areas. 

 

The monument supports 7,000 species, one quarter of which are endemic. Prominent species include the endangered hawksbill sea turtle, the threatened green sea turtle and the endangered Hawaiian monk seal, the Laysan and Nihoa finches, the Nihoa millerbird, Laysan duck, seabirds such as the Laysan albatross, numerous species of plants including Pritchardia palms, and many species of arthropods.

According to en.wikipedia