The geography of Guinea-Bissau is that of low coastal plains bordering the Atlantic Ocean. The country borders Senegal in the north and Guinea in the southeast.
The terrain of Guinea-Bissau is mostly low coastal plain with swamps of Guinean mangroves rising to Guinean forest-savanna mosaic in the east. A recent global remote sensing analysis suggested that there were 1,203kmò of tidal flats in Guinea-Bissau, making it the 28th ranked country in terms of tidal flat area.
Around 66 million years ago, an asteroid impact occurred 400 km off the west-African coast. The 2022 discovered Nadir buried Crater has a diameter of 9 km. The impact caused an earthquake of 6.5 magnitude and created a 1 km high tsunami. The combined forces could be an explanation for the extremely scarred coastline of Guinea-Bissau.
The lowest point on Guinea-Bissau is at sea level at the Atlantic Ocean. The highest point in Guinea-Bissau is Dongol Ronde with an elevation of . The Conservation Atlas of Tropical Forests: Africa authored in 1992 cites Fouta Djallon at as the highest.
Natural resources found in Guinea-Bissau include fish, timber, phosphates, bauxite, clay, granite, limestone and unexploited deposits of petroleum. 10.67% of the land is arable and 235.6 square kilometres are irrigated.
Natural hazards include a hot, dry, dusty harmattan haze that may reduce visibility during the dry season and brush fires. Severe environmental issues include deforestation; soil erosion; overgrazing and overfishing.
Near the Senegal border there have been historic sightings of the painted hunting dog, Lycaon pictus, but that endangered canid may now be extirpated in that locale.
Guinea-Bissau's climate is tropical. This means it is generally hot and humid. It has a monsoonal-type rainy season (June to November) with southwesterly winds and a dry season (December to May) with northeasterly harmattan winds.
Guinea-Bissau is warm all year around and there is little temperature fluctuation; it averages . The average rainfall for the capital city Bissau is although this is almost entirely accounted for during the rainy season which falls between June and September/October. From December through April, the country receives very little rainfall.
Global Forest Watch publishes annual estimates of tree cover loss and 2000 tree cover extent derived from time-series analysis of Landsat satellite imagery in the Global Forest Change dataset. In this framework, tree cover refers to vegetation taller than 5 m (including natural forests and tree plantations), and tree cover loss is defined as the complete removal of tree cover canopy for a given year, regardless of cause.
For Guinea-Bissau, country statistics report cumulative tree cover loss of from 2001 to 2024 (about 20.5% of its 2000 tree cover area). For tree cover density greater than 30%, country statistics report a 2000 tree cover extent of . The charts and table below display this data. In simple terms, the annual loss number is the area where tree cover disappeared in that year, and the extent number shows what remains of the 2000 tree cover baseline after subtracting cumulative loss. Forest regrowth is not included in the dataset.
Under the UNFCCC REDD+ framework, Guinea-Bissau has submitted a subnational forest reference emission level (FREL). On the UNFCCC REDD+ Web Platform, the country's 2019 submission for the terrestrial component of the National System of Protected Areas is listed as having an assessed reference level, while the other Warsaw Framework elements - a national strategy, safeguards, and a national forest monitoring system - are listed as "not reported".
The FREL was submitted in 2019 and technically assessed in 2020. It covers the REDD+ activity "reducing emissions from deforestation" and applies to the terrestrial component of the National System of Protected Areas, an area of about 750,000 hectares, or roughly 26 percent of the national territory. Using a 2007-2015 reference period, the assessed benchmark was 67,805.50 t CO2 eq per year. The technical assessment states that it represents the annual average of CO2 emissions from gross deforestation and was presented as an interim step towards a future national FREL.
The submission applies the FAO forest definition of land larger than 0.5 hectares with trees capable of reaching more than 5 metres in height and canopy cover of at least 10 percent, excluding predominantly agricultural or urban land. It includes above-ground biomass and below-ground biomass and reports CO2 only, while excluding deadwood, litter, soil organic carbon and non-CO2 gases. Although the REDD+ Web Platform lists the national forest monitoring system as "not reported", the modified submission states that a forest monitoring system and safeguards information system were being piloted in the protected-areas system.
This is a list of the extreme points of Guinea-Bissau, the points that are farther north, south, east or west than any other location.
Located near the border with Guinea, in the Bafatá / Gabu region; Guinea-Bissau is a very low-lying country, so even its highest point is modest compared to neighbors.