Equatorial Guinea's geography: a country in pieces on both sides of the equator

How Equatorial Guinea is split across the sea

The constitution of Equatorial Guinea, in its 1991 text as revised in 2012, defines the national territory as a list. It names the continental area known as Río Muni, then the islands of Bioko, Annobón, Corisco, Elobey Grande, Elobey Chico, Mbañe, Conga, Leva and Cocotero with their adjacent islets, then the river waters, the maritime zone, the continental shelf and the air space over all of it. The founding text describes the country as a set of pieces.

Britannica sorts the same list into two halves. Continental Equatorial Guinea is Río Muni, a roughly rectangular block bounded by Cameroon to the north and Gabon to the east and south. Insular Equatorial Guinea is five islands. Corisco and the two Elobeys sit close to the mainland in Corisco Bay, where Río Muni meets Gabon. Bioko lies in the Bight of Biafra off the Cameroonian coast, about 160 km north-west of the nearest point of Río Muni. Annobón is out on its own, 595 km south-west of Bioko and about 350 km west-south-west of Cape Lopez in Gabon.

The land boundary runs 539 km in all, 189 km with Cameroon in the north and 350 km with Gabon in the east and south, and everything else that bounds Equatorial Guinea is coast.

Why the published distances disagree

The figures for the gaps between the pieces vary with the publisher, and the variation is worth reading because it shows what each one measured. Bioko is 32 km from Cameroon in one Wikipedia article and 40 km in another, and 40 km in Focus on Geography's 2019 survey of the country. The Bioko article pairs its 32 km with a description of the strait itself, water only about 60 metres deep. Annobón is 595 km from Bioko in the Wikipedia geography article and about 650 km in Britannica.

The area of the mainland moves too. Wikipedia gives Río Muni as 26,003 km²; Focus on Geography gives 26,017 km². The country's record carries 28,051 km² for the whole territory, Britannica 28,052 km², and Protected Planet, working from its own base map, counts 26,877 km² of land when it calculates how much of it is protected. Protected Planet notes that its statistics can differ from official ones because of the base maps used, and the same caution applies to every figure in this paragraph.

Which side of the equator each piece lies on

Including Annobón, the territory runs from about 4° north to 2° south and from 5° to 12° east. The post-independence name refers to the country's position near the equator and to the African region of Guinea, and the position is near in a literal sense. The line itself crosses no land in Equatorial Guinea. Río Muni, Bioko, Corisco and the Elobeys are all in the northern hemisphere, and Annobón Province, about 155 km south of the equator, is the one part of the state on the other side.

The extreme points make the dispersal plain. The northernmost is Punta Europa on Bioko. The easternmost is near the village of Obileville in Río Muni. The southernmost, A Dyibó, and the westernmost, Punta Dyiscoj, are both on Annobón, so an island of 18 km² holds two of the four corners of the country.

How a set of pieces this scattered came to be one state is a question of treaties. Under the Treaty of El Pardo in 1778, Portugal ceded Fernando Po, which is now Bioko, together with Annobón and rights on the Guinea coast to Spain in exchange for territory in South America. Bioko kept the name Fernando Po for nearly five hundred years, was renamed Macías Nguema Biyogo between 1973 and 1979, and has been Bioko since 1979. Annobón takes its name from the day it was sighted, New Year's Day 1472.

Annobón sits about 150 km south-west of the island of São Tomé, and its forest is classed with that of São Tomé and Príncipe. The ecoregion that covers the whole of Annobón is the São Tomé, Príncipe and Annobón moist lowland forests, which it shares with its neighbour and with no other part of its own country.

How the mainland of Río Muni rises inland

Río Muni is the flatter ground. Its coast is a long stretch of beach with low cliffs toward the south, backed by a coastal plain about 20 km wide that is laid on sedimentary deposits. Behind the plain come coastal hills, and behind the hills a set of inland plateaus, the mesetas, which rise toward the frontier with Gabon. The hinterland is built mainly of ancient metamorphic rock that has been leached and eroded for a long time, and Britannica describes the resulting soils as relatively infertile.

Several ranges of hills cross the interior. The central range divides the basin of the Mbini, also called the Benito, to the north from the basin of the Utamboni to the south. The Niefang and Mikomeseng range north of the Mbini is somewhat lower. Britannica treats all of them as segments of the Cristal Mountains, which continue into Gabon. The town of Niefang carries a line in its name: it marked the traditional line between the Fang and the coastal groups, and the name means the limit of the Fang.

The heights are modest and imperfectly surveyed. The Key Biodiversity Areas factsheet for Monte Alen National Park, last assessed in 2001, says Monte Alen and Monte Mitra, both at about 1,250 metres and both inside the park, are thought to be the highest massifs on the mainland, and adds that altitudinal information is incomplete. None of the other sources consulted here prints a surveyed summit for the mainland.

Where the rivers of Río Muni run

The Mbini runs roughly east to west through the middle of Río Muni and divides it in half. It is called the Woleu in Gabon, and it can be navigated only in its first 19 to 20 km inland from the estuary. To the north the Campo, called the Ntem in French-speaking Africa, marks part of the frontier with Cameroon. The Utamboni drains the south. In the south-west the Muni, which gave Río Muni its name, is not a single river at all but the estuary of several rivers from Gabon and southern Equatorial Guinea, fringed with Central African mangroves.

The eastern border shows the gap between a line on paper and a line on the ground. The legal frontier with Gabon is the meridian at 11° 20′ east. The de facto border, Britannica records, follows the meandering course of the Kié River. The extent of the block was settled by the Treaty of Paris of 1900, which left Spain with about 26,000 km² of a mainland claim it had once put at some 300,000 km², stretching east as far as the Ubangi.

Why Bioko and Annobón stand on volcanoes

The two main islands are the work of a different geology. Both belong to the chain of volcanic peaks that runs south-west from Mount Cameroon on the mainland out across the Gulf of Guinea, which Focus on Geography calls the Bonny Islands and which Wikipedia calls the Cameroon line. São Tomé and Príncipe stand on the same chain. Bioko is built mostly of basalt, chiefly alkali basalt and hawaiite with some mugearite.

Bioko is about 70 km long from north-north-east to south-south-west and about 32 km across; Britannica measures it at 72 km by 35 km. It is shaped like a boot, with two large volcanic masses separated by a valley that cuts across the island at its narrowest point. In the north is Pico Basilé, once called Santa Isabel Peak, an extinct volcano. The country's record gives it 3,011 metres; Britannica gives 3,008 metres and the Wikipedia article on Bioko gives both 3,011 and 3,012. In the centre the Moca Peak and the Moca Heights carry upland country of an alpine type. The south is the Gran Caldera range, rugged, cut by torrents and dotted with crater lakes. The scientific reserve there is formed of two large steep-sided volcanoes and spans sea level to 2,261 metres.

The island's 195 km of coast is mostly a cliff about 20 metres high, broken by small inlets and beaches. The south coast is very steep and dangerous to shipping, and San Antonio de Ureca there is one of the more isolated settlements on Bioko. The north is lower and has the harbours: Luba, and Malabo, whose harbour is built on the partly sunken rim of a volcano. The Musola River and other torrents are used for hydroelectric power.

When Bioko was part of the mainland

Bioko sits on the African continental shelf. The strait that separates it from the mainland is about 32 km wide and only about 60 metres deep, and during the Pleistocene, when sea levels were lower, the island was joined to Africa. It was cut off around 10,000 years ago at the end of the last glacial period. Its lowland forest is classed in to the Cross-Sanaga-Bioko coastal forests ecoregion, shared with the adjacent coast of Cameroon and Nigeria, and its highlands are grouped with Mount Cameroon's in the Mount Cameroon and Bioko montane forests.

Annobón is smaller and lower. Britannica describes it as a conglomeration of volcanic cones, including Mount Santa Mina and Mount Quioveo, with its high ground at about 670 metres, on an island not quite 6 km long and 3 km wide. Its coast is abrupt except in the north, and the principal volcanic cone holds a small lake.

Why rain falls so unevenly across Equatorial Guinea

The whole country has an equatorial climate of high temperature, heavy rain and cloud for most of the year. Inside that, how wet a place is comes down to its altitude and its distance from the sea.

On Bioko the gradient runs north to south across one island. The Wikipedia article on Bioko attributes the gradient to the relief and the West African monsoon, and Britannica describes the southern rain as brought by monsoon winds. Bioko's dry season runs from November to March and the rest of the year is wet. The mean temperature is about 25 °C and barely moves through the year, with afternoons near 32 °C and nights near 21 °C, and the sky is overcast most of the time. Malabo's temperatures run from 16 °C to 33 °C, while on the Moka Plateau in the south the normal daily high is only 21 °C.

On the mainland the rain falls in two wet seasons, February to June and September to December, and it falls harder on the coast than inland. Bata takes about 2,400 mm a year, most of it in September, October and November. The interior around Mikomeseng gets less than two thirds of that. Temperatures average about 26 °C, the maxima a little lower than Bioko's, and the relative humidity is higher.

The two calendars do not line up. Between June and August Río Muni is in its dry spell while Bioko is in the wet; between December and February Bioko is dry and the mainland is not. For about half of each year the two main pieces of the country are in opposite seasons.

Annobón has a climate of its own again, humid and subject to violent windstorms. Rain or mist falls on it every day, and Wikipedia records that a cloudless day has never been registered there. Violent windstorms and flash floods are the natural hazards listed for the country as a whole.

What the forest and the reserves hold

Global Forest Watch measured 26,546 km² of tree cover above 30% canopy density in 2000, close to 95% of the land area, and a cumulative loss of 155,331 hectares between 2001 and 2024, about 5.9% of that baseline. Focus on Geography counted more than 140 types of tree in the country's forests in 2019, mahogany, ebony and rubber among them, and recorded dwarf antelope, hippopotamus, elephant, gorilla and four species of sea turtle.

The forest is classed differently on each piece. Río Muni lies in the Atlantic Equatorial coastal forests, with mangroves along the coast and in the Muni estuary. Bioko's lowlands are Cross-Sanaga-Bioko coastal forest and its heights are montane forest. Annobón, as noted, has the São Tomé ecoregion to itself within the country.

Protected Planet's profile of October 2026 counts 16 protected areas. Thirteen are national designations, three national parks, two natural monuments, six nature reserves and two scientific reserves, and three are Ramsar wetlands of international importance. Together they cover 18.99% of the land, 5,103 km², and 0.27% of the sea, 815 km² of a marine area of 304,144 km².

How the reserves sit on mainland and island

On the mainland the main block is Monte Alen National Park, whose Key Biodiversity Area covers 1,939 km² and lies entirely within protected land. It is primary rainforest from 300 to 1,250 metres, 95% forest, bordered by the Uoro River on the west and the road from Niefang to Gabon on the east. It has been managed since 1992 by ECOFAC, a project funded by the European Union; the park was doubled in October 1998 when Monte Mitra was added, and extended to the south under the protected area law of 2000. At least 265 species have been recorded there, and the factsheet notes that large mammals, gorillas among them, are still hunted inside it.

On Bioko two protected areas cover about 40% of the island: Pico Basilé National Park in the north, created in 2000 and about 32,256 hectares, and the Gran Caldera de Luba Scientific Reserve in the south, about 51,000 hectares. Bioko has seven species of diurnal primate, including the endemic Pennant's red colobus, and all seven occur inside the southern reserve. A paved road completed in 2015 cut across it, opening ground the terrain had kept closed. Acoustic sensors placed in the reserve from January 2018 to January 2020 recorded gunshots at every site, including inside the Caldera de Luba itself. UNESCO designated Bioko a biosphere reserve in 2025.

The country has no site on the World Heritage List and, as UNESCO noted in August 2025, no Tentative List either. A UNESCO mission that month visited candidate sites put forward by the state, and two of the three it named were natural ones: Monte Alen National Park on the mainland and the Caldera de Luba reserve on Bioko.

Where the sea extends the national territory

Counted with its sea, Equatorial Guinea is mostly water. It claims a territorial sea of 12 nautical miles and an exclusive economic zone of 200, and the zone covers 303,509 km², close to eleven times the land area. Protected Planet's own marine base, 304,144 km², comes out at almost the same size.

Some of those islets were disputed. Gabon claimed Mbanié, Cocoteros and Conga from 1972. On 19 May 2025 the International Court of Justice ruled on the dispute, and Wikipedia and the World Bank both record the ruling as being in Equatorial Guinea's favour. The constitution had already listed Mbañe, Conga and Cocotero among the islands of the national territory.

The oil and gas fields lie offshore too. Spanish government geologists first found evidence of oil in the waters off Bioko, and Focus on Geography described the country's crude oil infrastructure in 2019 as almost entirely offshore. The principal production area, the Zafiro Field, lies about 68 km north-west of Bioko near the Cameroonian coast and is worked by floating production and storage vessels moored over the wells. Gas from the nearby Alba Field comes ashore at Punta Europa, the northernmost point of the country, to a processing plant west of Malabo.

How the split shapes where people live

Bioko holds a little over 2,000 km² of the territory and a large share of its people. The 2015 census counted 335,048 on the island, 271,008 of them in the Malabo district, 29,366 in Baney, 26,331 in Luba and 8,343 in Riaba. The national population stood at 1,847,549 in 2023. The Bubi are indigenous to Bioko and the Fang to the mainland, and Fang migration to the island has run since the 20th century.

The capital has moved across the water. Malabo, on its volcanic harbour, was the capital until a presidential decree of 2 January 2026 named Ciudad de la Paz, on the mainland, in its place, giving government services a year to transfer. The new city, earlier called Oyala and Djibloho, lies about 172 km inland from the Atlantic coast of Río Muni and was cut entirely out of the rainforest; Focus on Geography described twin 500-metre suspension bridges over the Wele River there in 2019. The record gives it a population of 2,000 in 2022.

Movement between the pieces runs by sea and by air, with airports at Malabo, at Bata and on Annobón. The ports are Malabo and Bata, whose harbour was enlarged in the 1980s, with Mbini and Kogo as minor calls on the mainland coast. A ring road links Bioko's four main towns, Malabo, Luba, Baney and Riaba. Focus on Geography put the national highway system at 2,280 km in 2019, a figure that includes the ring road around Bioko, and described a port built on Annobón for large ships and passenger ferries.

Access to the outer pieces is regulated. The Spanish foreign ministry's travel advice, as it stood in October 2026, said an official permit is required to visit the Moka valley, Ureka and Pico Basilé on Bioko, and an authorisation in every case to travel to Corisco or Annobón, while recreational sailing is prohibited in Bioko's waters. The same advice reported the land borders of the mainland closed from 15 December 2025 for an indefinite period, which leaves the sea and the air as the ways in.