The largest river in Colombia. Originated in the wilderness of pappas at an altitude of 3,600 meters in the southwest, it travels northward in the valley between the East Cordillera Mountains and the Central Cordillera Mountains, and flows into the Caribbean Sea in the north of Barranquilla. Long 1560 km, with a drainage area of 260,000 square kilometers. The mainstream develops in the 80-kilometer-wide fault valley and flows through the savanna area. The average annual precipitation in the middle and upper reaches is above 1000mm, and the average annual precipitation in the lower reaches is about 740 mm. The average annual flow of this estuary is 8000 cubic meters per second. The main tributaries are Cauca River, San Jorge River and Cesar River. The river is relatively straight, with many rapids and shoals; After flowing into the northern lowland swamp, the velocity drops sharply, and sediment often silts up the estuary. Barranquilla is an estuary, navigable to Larada (970 kilometers), which connects the mainland and the Caribbean sea ports. This valley is rich in coffee, bananas, cotton and tobacco. Downstream is the oil-producing area. There are abundant freshwater fish in the river.