Geography of Nauru

Its land area is 21 km² (8.1 sq mi), and it has a 30-kilometre coastline (19 mi). Maritime claims are an Exclusive Economic Zone of 308,480 km² (119,100 sq mi) with 200-nautical-miles (370 km), and a 12-nautical-mile (22 km) territorial sea.

The climate is tropical with a monsoon rainy season from November to February.

A sandy beach rises to the fertile ring around raised fringing coral reefs. The raised phosphate plateau ('Topside') takes up the central portion of the island. The highest point is 213 ft (65 m) above sea level, along the plateau rim.

Nauru's only economically significant natural resources are phosphates, formed from guano deposits by seabirds, and fisheries, particularly for tuna.

Due to being surrounded by corals and sandy beaches, the island houses no natural harbours, nor any rivers or substantial lakes.

Nauru has a unique navigational system, which is only capable of being used on the island.

Geology of Nauru

Nauru is a raised coral atoll positioned in the Nauru Basin of the Pacific Ocean, on a part of the Pacific Plate that formed at a mid-oceanic ridge at 132 Ma. From mid-Eocene (35mya) to Oligocene times, a submarine volcano built up over a hotspot and formed a seamount composed of basalt. The seamount is over 4300 metres high. This hotspot was simultaneous with a major Pacific Plate reorganisation. The volcano was eroded to sea level and a coral atoll grew on top to a thickness of about 500 metres. Coral near the surface has been dated from 5 Mya to 0.3 Mya. The original limestone has been dolomitised by magnesium from seawater. The coral was raised above sea level about 30 metres and is now a dolomite limestone outcrop which was eroded in classic karst style into pinnacles up to 20 metres high. To at least a depth of 55 metres below sea level, the limestone has been dissolved forming cavities, sinkholes, and caves. Holes on the topside of the island were filled up by a phosphate layer up to several metres thick.

Anibare Bay was formed by the underwater collapse of the east side of the volcano. Buada Lagoon was formed by solution of the limestone when the sea level was lower, followed by collapse.

Nauru is moving at 104 mm (4.1 in) per year to the northwest along with the Pacific Plate.

Freshwater can be found in Buada lagoon, and also in some brackish ponds at the escarpment base in Ijuw and Anabar in the northeast. There is an underground lake in Moqua Cave in the southeast of the island. Since there are no streams or rivers on Nauru, water must be gathered from roof catchment systems. Water is also brought to Nauru as ballast on ships returning for loads of phosphate.