Anaa, Nganaa-nui (or Ara-ura) is an atoll in the Tuamotu archipelago, in French Polynesia. It is located in the north-west of the archipelago, 350 km to the east of Tahiti. It is oval in shape, 29.5 km in length and 6.5 km wide, with a total land area of 38 km² and a population of 500. The atoll is made up by eleven small barren islands with deeper and more fertile soil than other atolls in the Tuamotus. The lagoon is shallow, without entrance, and formed by three main basins. Although it does not have any navigable access, the water of the lagoon renews by several small channels that can be crossed walking.