Motu One (Marquesan for "Sand Island"; French: Îlot de Sable) is the name of a small sandbank with no vegetation, located on the western edge of a coral reef; the only atoll in the Marquesas Islands.

The reef is approximately 5 kilometres (3.1 mi) in diameter, and the islet has a surface area of less than one hectare, rising only a few feet above sea level and changing shape regularly as the action of the currents deposits and removes sand.

Although Motu One was reportedly visited by Marquesans from islands in the region, primarily on egg-collecting missions, there is no archaeological evidence that it was ever inhabited.

The first Westerners to sight the islet were those on the 1813–1814 voyage of the American commander Commodore David Porter, who named it Lincoln Island.

[1] There are a wide variety of pelagic birds nesting on the islets including a subspecies of the southern Marquesan reed warbler, the Mohotani Marquesan warbler (Acrocephalus mendanae consobrina).