Hiva Oa is the largest and most fertile of the southern Marquesas islands and second only to
Nuku Hiva in size. Similar to all the larger Marquesas, Hiva Oa features cliffs abruptly rising from the ocean to a rugged interior spine of volcanic mountains, ridges, and deep, isolated valleys. Unlike most other Polynesian islands near the equator, no fringing
coral reefs protect Hiva Oa from the pounding of the ocean, and only a few sheltered anchorages and sandy beaches are scattered around the coast. Travel along the shoreline is by boat, as most of the coastal terrain is too rugged for roads. A few dirt roads traverse the interior, linking seacoast villages and settlements.
Atuona Airport is located at an elevation of on a plateau near the center of the island and has an asphalt-surfaced runway long with daily flights to other Marquesas islands and
Tahiti. The outstanding geologic characteristic of Hiva Oa is the collapsed volcano
Temetiu. Semi-circular
Ta'a Oa bay, also called the Bay of Traitors, is in the crater of the volcano whose walls rise sharply above the bay. Within Ta'a Oa are Atuona Bay and adjacent
Taha Uku, which are the best anchorages on the island. Hiva Oa is separated from the nearby island of
Tahuata to its south by a wide channel called
Ha'ava or the Canal de Bordelais.
Climate Temperatures in the Marquesas are stable year-round, but precipitation is highly variable. Precipitation is much greater on the north and east (windward) parts of the islands and much less on the western (leeward) parts. Droughts, sometimes lasting several years, are frequent and seem to be associated with the
El Niño phenomenon. The highest annual rainfall recorded in Atuona is ; the lowest is .
Geology The island is of volcanic origin. Geologically, Hiva Oa belongs to the Marquesas Linear Volcanic Chain, which formed from a
hot spot on the Pacific Plate and is moving west-northwest at a rate of 103 to 118 mm. per year. The magmatic rocks on the island are between 1.63 and 4.26 million years old, but volcanic activity has not yet been completely extinguished. Not far from the road from Atuona to Ta'aoa, further west, some mud pots and small
solfataras can be seen.
Flora Like Nuku Hiva, Hiva Oa, the second-largest island in the archipelago, has a relatively high
biodiversity for the South Pacific. A total of 205 native plants - 24 of them endemic - and 178 exotic species have been identified. Among the richest and most widespread native species on the island are ferns with a high number of endemic species. They cover large areas of the inaccessible, humid, and shady valleys' incisions. Among the idiocorophytes (ancient autochthonous species) are probably the coconut palm and the screw tree, which are widespread in the lowlands. Anthropochorophytes, such as
breadfruit trees and Tahitian chestnut (Inocarpus edulis), already introduced by
Polynesian settlers, predominate in the lowland and midland regions. A threat to native plant communities could be bamboo, which is not native to the island and has already formed extensive groves in some places. In the higher, more inaccessible areas of the island, the natural
habitats remain almost unchanged. The north, shaded from wind and rain by the mountains, is largely arid.
Fauna The
fauna of the Marquesas Islands is limited to land and sea birds,
insects, reptiles,
butterflies, and spiders. The reptiles of this area include a few species of gecko and skinks. Birds include the Marquesas warbler (
Acrocephalus mendanae mendanae) endemic to Hiva Oa and the neighboring island of
Tahuata, the
Marquesan Kingfisher, the
Marquesan monarch, and several species of
dove. The island used to be home to
Marquesan swamphen, before they went extinct. There are no animals that are dangerous to humans. The nono fly, a type of black fly which occurs in the interior, is extremely unpleasant. ==Population==