Colombia is the only country in South America to touch both Atlantic and Pacific oceans.

It is bordered to the east by Venezuela and Brazil, to the south by Ecuador and Peru, to the north by the Caribbean Sea, to the northwest by Panama, and to the west by the Pacific Ocean. Colombia also shares maritime borders with Jamaica, Haiti, the Dominican Republic, Honduras, Nicaragua and Costa Rica.

As part of the Pacific Ring of Fire, a region of the world subject to earthquakes and volcanic eruptions, Colombia is dominated by the Andes mountains.

In Colombia the Andees are divided into three branches known as cordilleras:

- Cordillera Occidental, running adjacent to the Pacific coast and including Cali,
- Cordillera Central, running between the Cauca and Magdalena river valleys and including Medellín, Manizales and Pereira, and
- Cordillera Oriental, extending north east to the Guajira Peninsula, including Bogotá, Bucaramanga and Cúcuta.

Peaks in the Cordillera Occidental exceed 13000 feet (4000 m), and in the Cordillera Central and Cordillera Oriental reach 18000 feet (5500 m).

At 8800 ft (2700 m), Bogotá is the highest city of its size in the world.

East of the Andes lies the savanna of Los Llanos, part of the Orinoco River basin, and in the far south-east, the jungle of the Amazon rainforest. Together these lowlands comprise over half Colombia's territory, however they contain less than 3% of the population.

To the north, the Caribbean coast, home to 20% of the population and the location of the major port cities of Barranquilla and Cartagena, generally consists of low-lying plains, but it also contains the Sierra Nevada de Santa Marta mountain range, which includes the country's tallest peaks (Pico Cristobal and Pico Simon Bolivar), and also the Guajira Desert.

By contrast, the narrow and discontinuous Pacific coastal lowlands, backed by the Serranía de Baudó mountains, are covered in dense vegetation and sparsely populated. The principal Pacific port is Buenaventura.