Colombia is the fourth-largest country in South America and the only one with coasts on both the Pacific and Caribbean. It shares borders with Panama (to the northwest), Venezuela (east), Brazil (southeast), Peru (south) and Ecuador (southwest). Colombian territory also includes the San Andrés and Providencia island groups, 700km (435mi) northwest of the mainland, in the Caribbean Sea. The archipelagoes are 230km (140mi) east of Nicaragua.

The western part of the country is mostly mountainous: the 8000km (5000mi) Cordillera de los Andes runs the length of South America and, on reaching Colombia, splits into three ranges (Cordillera Occidental, Cordillera Central and Cordillera Oriental). Two valleys - Valle del Cauca and Valle del Magdalena - are sandwiched between the three cordilleras; their rivers flow northwards, more or less parallel, until the Cauca River joins the Magdalena River and flows into the Caribbean. Apart from the three Andean chains, Colombia boasts the Sierra Nevada de Santa Marta, the highest coastal mountain range in the world. Over 50% of the territory east of the Andes is lowland or covered by thick rainforest crisscrossed by rivers and their tributaries.

Among Colombia's geographical curiosities are deserts in the northeast; the jungle of the Pacific coast (which holds a record for highest rainfall); and the Serranía de la Macarena, an isolated mountain formation rising 1000m (3000ft) from the eastern plains.

Colombia claims to have the highest number of species of plants and animals per unit area of any country in the world. Its animals include jaguars, ocelots, peccaries, tapirs, deer, armadillo, numerous species of monkey and the rare spectacled bear. There are more than 1550 recorded species of birds (more than in the whole of Europe and North America combined), ranging from the huge Andean condor to the tiny hummingbird. Equally abundant marine life includes the predacious piranha and the electric eel. Colombia's herbariums have classified over 130,000 plants, including Victoria Amazonica, which is similar to a water lily and has leaves large and strong enough to support a child.

The country's network of reserves includes 33 national parks, six small areas called santuarios de flora y fauna, two reservas nacionales and one area natural única. Their combined area constitutes 7.9% of Colombia's territory.

As the country lies close to the equator, the average temperature varies little throughout the year. Temperatures do, however, vary with altitude; as a general rule, the temperature falls about 6 degrees centigrade with every 1000m (3280ft) increase in altitude. Colombia's equatorial climate features two seasons: verano (dry) and invierno (wet). But because of the country's complex geographical and altitudinal factors, there is no universal pattern of seasons. One area that does have a definite pattern is Los Llanos, in the east, where the dry season falls between December and March and the rest of the year is wet.

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