With the exception of a permanent ranger station, Cocos Island is an uninhabited island approximately 340 mi (550 km) from the Pacific shore of Costa Rica. With an area of about 9.2 sq. mi (23.8 sq. km) and a perimeter of roughly 14.4 mi (23.3 km), this island is almost rectangular in shape.
Cocos Island is an oceanic island of both volcanic and tectonic origin. It is the only emergent island of the Cocos Plate, one of the earth’s minor tectonic plates. Scientific testing established the age of the oldest rocks in the range of 1.91-2.44 million years.
Cocos Island Geology
Cocos Island is composed primarily of basalt, which in turn is formed by cooling lava. The geology is rather mountainous and irregular, and the summit’s name is Cerro Iglesias.
In spite of its mountainous character, there are flatter areas between 656-853 ft. (200-260 m) in elevation in the central part of the island. These areas are perhaps a transitional stage of the geomorphological cycle of V-shaped valleys.
With four bays, three of them in the north side (Wafer, Chatham, and Weston), Cocos Island has a large number of short rivers and streams that drain the abundant rainfall into them. Due to a large range of about 300-foot (91.4 m) high cliffs that ring much of the island, the easiest point of entry is at Chatham Bay.
Cocos Island Climate
The largest rivers are Genio and the Pittier, which drain into Wafer Bay. The mountainous landscape and the tropical climate combine to create more than 200 waterfalls throughout the island.
The island’s soils are Entisols, which are highly acidic and could be easily eroded by the island’s high rainfall on the steep slopes if it was not for the dense forest coverage. Root systems are very critical in protecting from erosion.
Cocos Island is famous for the cloudiness and precipitation that is constant throughout the year. This makes the climate humid and tropical with an average annual temperature of 74.5F (26.6C), and an average annual rainfall of more than 275 in (699 cm). Rainfall is high throughout the year, although lower from January through March and slightly lower during late September and October.
Cocos Island Flora and Fauna
A number of oceanic currents from the central Pacific Ocean converge on the island also have an important influence on the weather. Cocos Island is home to dense and exuberant tropical moist forests.
It is, in fact, the only oceanic island in the eastern Pacific region with such rainforests and their characteristic types of flora and fauna. The cloud forests at higher elevations are also unique in the eastern Pacific.
The island was never part of a continent, so the flora and fauna arrived via long-distance dispersal from North and South America. Cocos Island has, therefore, a high proportion of unique endemic species.