Atiu

Atiu (27 sq.km/16.7mi; up to 72m/236ft), almost square in shape, lies northeast of Rarotonga. The third largest of the Cook Islands, it consists of a much weathered central volcanic massif in the form of a shallow dome, the slopes of which are slashed by radial gorges. Round the foot are swampy depressions (taro land) completely surrounding the island's volcanic core. These in turn are succeeded by a 1km/.6mi wide raised platform of coralline limestone (makatea), which falls down to the sea, at some points edged by cliffs 6-9m/20-30ft high. The surface of the makatea is much affected by karstic action, with underground cave systems. Surface water drains down to the coast through dolines and caves. The island is surrounded at a distance of 45-90m/147-295ft by a surf-lashed reef some 90m wide, with gaps at intervals that allow small ships to reach the landing stages.

From Taunganui Landing a road cuts through the interior of the island, with narrow roads or tracks leading to individual houses or to the taro swamps.