The Gambia has an area of 11,295 sq km (4,361 sq mi), less than twice the area of the state of Delaware. It occupies both sides of the lower Gambia River, which is the dominating natural feature of the country. The river cuts a winding course through a low plateau, which slopes from a maximum elevation of 50 m (160 ft) down to sea level. The river narrows to 4 km (2.5 mi) at Banjul and then broadens, providing an excellent harbor.
The river banks are low and fringed with mangroves for the first 130 km (80 mi) from the coast. Behind the mangroves are swamps that are suitable in many places for rice cultivation. The slightly elevated and rather flat land that slopes up from the river valley has a light, sandy soil on which the villages are built and where peanuts and grain crops such as millet and sorghum are grown
The Gambia has a tropical climate with well-defined rainy and dry seasons. The rainy season lasts from June to October. Agricultural production must be concentrated during this season. Rainfall varies considerably from year to year, averaging about 1,020 mm (about 40 in). But it ranges from less than 750 mm (30 in) to more than 1,500 mm (60 in).
The dry season extends from November to May. During the months of March, April, and May, the harmattan, a hot, dry, dusty wind, frequently blows from the Sahara, bringing temperatures that exceed 38°C (100°F) to the interior of the country. Temperatures along the coast range from 18°C (65°F) in winter to 32°C (90°F) in summer
The main natural resource of The Gambia is the Gambia River, one of Africa’s best navigable waterways. Small ocean-going vessels can go upstream for about 200 km (125 mi) from the coast, and smaller craft can continue for another 200 km. The country’s soil is mostly poor and sandy, except in the swamps along the rivers. However, this sandy soil is ideally suited for the cultivation of peanuts, upon which the economy depends. Fish are increasing in economic importance. Seismic surveys have indicated the possibility that petroleum and natural gas exist offshore.
The natural vegetation of the upland areas consists of wooded, but open, savanna. However, intensive clearing for agriculture has destroyed most of the original tree cover. The government has set aside some areas as forest parks and has planted trees in other areas. Mangroves grow in abundance along the Gambia River, and oil palms have been planted on plantations.
Wild animal life has become scarce in The Gambia, but bird life is exceptionally rich, especially in the large mangroves near the rivers. The animals most commonly seen include monkeys, baboons, wild boar, and several species of antelope. Hippopotamuses and crocodiles can be seen in the central and upper zones of the Gambia River. Lions and hyenas live in the Abuko Nature Reserve, 24 km (15 mi) from Banjul
The Gambia has lost 91 percent of its original forest habitat, which has been cleared for agriculture and fuel wood. As a result, many of the big-game animals are no longer found wild in the country, although some parks and nature reserves have been established, including Baboon Island, also known as The River Gambia National Park. With government incentives encouraging growth in the number of fishing companies, overfishing has emerged as a problem.
Saltwater has intruded farther upriver, causing agricultural lands to become saline, and desertification has increased. Water-borne diseases are prevalent along the river and its estuaries, where large numbers of people live