Fatu Huku is a small island in the Marquesas Islands, nearly halfway between Hiva ‘Oa and Nuku Hiva.

Fatu Huku is located at 9.43°S latitude and 138.93°W longitude, and consists primariliy of a high plateau that rises to 361 m (1,184 ft.).

The island was likely only ever inhabited in legend. The story of the demigod Tana-Oa, patron of fishermen, says that the island was once fertile and green, until the sea, jealous of its beauty, turned the island upside down. It is said that this is how the island came to have coral on its flat top.

On the plateau are a number of small platforms, which were likely used in sacrificial ceremonies by the fishermen who frequented its waters in pre-European times.