Motu One (Marquesan for "Sand Island"; in French the islands are sometimes called Îlots du Sable) is the name of two small sandy islands on the western edge of a coral reef. At approximately , it is the northernmost of the Marquesas Islands, located about 30 km (18 mi.) northeast of Eïao and 15 km (9 mi.) northeast of Hatutu.
The reef is approximately 5 km (3 mi.) in diameter, and the islands rise only a few feet above sea level. The only vegetation is low-growing shrubs and grasses. Sea turtles and a wide variety of seabirds nest on the islands.
Although Motu One was reportedly visited by Marquesans, primarily on egg-collecting missions, there is no archaeological evidence that they were ever inhabited. The first Westerners to sight the islands were on the 1813-1814 voyage of the American commander Commodore David Porter, who named the island Lincoln Island. Subsequent explorers also called the islands Sand Island(s). Since 1992, the whole reef and island ecosystem have been protected as the Motu One Reserve.