The Republic of Equatorial Guinea may be divided into three regions whose areas and forests vary greatly:
Río Muni the country's mainland covers 26 017 km2 and has the form of a trapezium, bordered on the north (latitude 2° 10´ N) by Cameroon, on the east (longitude 11° 20´ E) and south (latitude 1° N) by Gabon, and on the west by the Atlantic (the Gulf of Guinea). The country is 130 km from north to south and an average of 200 km from west to east. The terrain is gently rolling and heavily forested. The Mbini (formerly Benito) River drains about 60 percent of the area. It also includes the coastal islets of Corisco, Elobey Grande, and Elobey Chico.
The island of Bioko (formerly Macías Nguema Biyogo and previously Fernando Póo) farther to the north (average latitude 3° 30´ N) in the Bight of Biafra (Bonny) is made up of the cones of two volcanoes that reach a height of 3 008 m (Pico de Santa Isabel). The island, primarily of volcanic origin, is mountainous and thickly wooded, with a steep, rocky coast.
The smaller and more distant (latitude 1° 24´ S) island of Annobón with an area of 44 km2 and composed of a volcano 900 m high.
The total area of Equatorial Guinea is 28,051 km2.
Río Muni, the mainland, is made up of a sedimentary coastal strip 15 km wide, with a tiered escarpment of geological strata lying north-west to south-east (leptite at 300 m and diorite and gabbro at 500 m), rising in the south-east to a 600-m granite plateau, which is the western extension of the Gabonese Crystal Mountains. The coastal area is fairly flat and even but the terrain is more rugged in the interior, with some mountains reaching a height of 1 100 to 1 200 m.
Equatorial Guinea has a hot, humid tropical climate with the average annual temperature in Malabo about 25° C. Rainfall varies from 1 800 mm in the north-east to 3 500 to 4 000 mm in the south-west (Cape San Juan) of Río Muni, and over 2 500 mm in Bioko, reaching over 10 000 mm in some places. The wettest season is December through February.
The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.