Marutea Atoll (Marutea Sud), also known as Lord Hood Island, Marutea-i-runga, and Nuku-nui, is an atoll in the far southeast of the Tuamotu group of French Polynesia. It lies in the east-northeast part of the Gambier (commune), about 72 km northeast from Maria Atoll.

Marutea Atoll is irregular in shape and bound by a reef broken by passes into the 112 km2 (43 sq mi) lagoon. It is 20 km (12 mi) long with a maximum width of 8 km (5 mi) and a land area of approximately 12 km2 (5 sq mi). Its islands are low and flat and the main village, Auorotini, is located at the northern end of the atoll. It is populated by ex Gambier Islanders looking for pearls and maintaining the pearl farms on the atoll.