Colombia usually classifies its geography into five
natural regions, from the
Andes mountain range, a region shared with
Ecuador,
Venezuela; the
Pacific Ocean coastal region, shared with
Panama and
Ecuador; the
Caribbean Sea coastal region, shared with Venezuela and Panama; the
Llanos (plains), shared with Venezuela; to the
Amazon rainforest region shared with Venezuela,
Brazil,
Peru and Ecuador. Colombia is one of only two South American countries that have coastline on both the Atlantic and Pacific oceans, the other being Chile.
The World Factbook does not differentiate between the
Amazon region of Colombia (predominantly jungle) and the Orinoquia region of Colombia (predominantly plains). It suggests dividing the country into four geographic regions: the Andean highlands, consisting of the three Andean ranges and intervening valley lowlands; the Caribbean lowlands coastal region; the Pacific lowlands coastal region, separated from the Caribbean lowlands by swamps at the base of the Isthmus of Panama; and eastern Colombia, the great plain that lies to the east of the
Andes Mountains. The chief western mountain range, the
Cordillera Occidental, is a moderately high range with peaks reaching up to about (4,670 m). The
Cauca River Valley, an important agricultural region with several large cities on its borders, separates the Cordillera Occidental from the massive
Cordillera Central. Several snow-clad volcanoes in the Cordillera Central have summits that rise above . The valley of the slow-flowing and muddy
Magdalena River, a major transportation artery, separates the Cordillera Central from the main eastern range, the Cordillera Oriental. The peaks of the Cordillera Oriental are moderately high. This range differs from Colombia's other mountain ranges in that it contains several large basins. In the east, the sparsely populated, flat to gently rolling eastern lowlands called
llanos cover almost 60 percent of the country's total land area. This cross section of the republic does not include two of Colombia's regions: the Caribbean coastal lowlands and the
Sierra Nevada de Santa Marta, both in the northern part of the country. The lowlands in the west are mostly swampy; the reed-filled marshes of the area are called
ciénagas by the people of Colombia. The
Guajira Peninsula in the east is semiarid and is occupied primarily by indigenous peoples. The Sierra Nevada de Santa Marta is a spectacular triangular snowcapped block of rock that towers over the eastern part of this lowland. Here can be found the highest peak of the country, named
Pico Cristobal Colon (5775 m). This was his alternative to the canal that was eventually built further west on the isthmus of what became
Panama after it gained independence in the early 20th century. Although the US sent an expedition to explore Kennish's proposal, the concept was not developed at the time. Colombia refused a later US offer to build a canal. After independence, in 1903 Panama made a treaty with the US to support construction of the
Panama Canal. Colombia occupies most of the Andes mountain range northern extremity, sharing a bit with Venezuela; the range splits into three branches between the Colombia-Ecuador border. In the 1980s, only three percent of all Colombians resided in the Pacific lowlands, a region of jungle and swamp with considerable but little-exploited potential in minerals and other resources. Later in the 20th century, it was threatened by mining-related deforestation, as gold mining proceeded by both major companies and artisan miners.
Buenaventura is the only port of any size on the coast. To the east, the Pacific lowlands are bounded by the Cordillera Occidental, from which numerous streams run. Most of the streams flow westward to the Pacific, but the largest, the navigable
Río Atrato, flows northward to the Golfo de Urabá. Its river settlements have access to the major Atlantic ports and consequently are commercially related primarily to the Caribbean lowlands hinterland. To the west of the Río Atrato rises the
Serranía de Baudó, an isolated chain of low mountains that occupies a large part of the region. Its highest elevation is less than 1,800 meters, and its vegetation resembles that of the surrounding tropical forest. The
Atrato Swamp, in Chocó Department adjoining the border with Panama, is a deep muck sixty-five kilometers in width. For years it has challenged engineers seeking to complete the
Pan-American Highway. This stretch, near
Turbo, where the highway is interrupted, is known as the Tapón del Chocó (Chocon Plug). A second major transportation project in Chocó Department has been proposed. A second inter-oceanic canal would be constructed by dredging the Río Atrato and tributary streams and digging short access canals. Completion of either of these projects would do much to transform this region, although it could have devastating consequences on the fragile, tropical forest environment.
Orinoquía region The area east of the Andes includes about 699,300 square kilometers or three-fifths of the country's total area, but Colombians view it almost as an alien land. The entire area, known as the eastern plains, was home to only two percent of the country's population in the late 1980s. The Spanish term for
plains (
llanos) can be applied only to the open plains in the northern part, particularly the Piedmont areas near the Cordillera Oriental, where extensive cattle raising is practiced. The region is unbroken by highlands except in
Meta Department, where the
Serranía de la Macarena, an outlier of the Andes has unique vegetation and wildlife believed to be reminiscent of those that once existed throughout the Andes.
Amazon region Many of the numerous large rivers of eastern Colombia are navigable. The
Río Guaviare and the streams to its north flow eastward and drain into the basin of the
Río Orinoco, a river that crosses into Venezuela and flows into the Atlantic Ocean. Those south of the Río Guaviare flows into the
Amazon Basin. The Río Guaviare divides eastern Colombia into the llanos subregion in the north and the tropical rainforest, or selva, subregion in the south. ==Climate==