Manuae is a true atoll sitting on the peak of a submerged volcano which descends 4000 meters to the ocean bed. It is made of two horseshoe-shaped islets, "Manuae" to the west and "Te Au O Tu" to the east, with a total area of 6.17 km²on either side of a lagoon about 7 km x 4 km. Manuae has an area of 2.1 km², and Te Au O TU of 3.9 km². The lagoon is 13 km² in size, shallow and subject to large shifting sand banks. A coral reef surrounds the atoll and there is no passage through the reef.