From the grasslands of the narrow coastal plain, the land rise into the rounded, low hills of the Bateka Plateau, and the elevated, mountainous regions along its western border with Gabon.
Mount Berongou, the Congo's highest point, is located in the upper reaches of the Crystal Mountains on the border with Gabon. It rises to about 903 meters (2,963 feet).
Further inland and to the northeast, the land flattens, all covered by a dense equatorial rainforest.
The Congo River is the longest river in the Congo, the second-longest river in Africa, and the sixth-longest river in the world, with a total length of about 4,700 km (2,920 mi).
The Stanley Pool is a lake formed by the widening of the Congo River. It lies between the borders of the Congo and the Democratic Republic of the Congo. It covers an area that is about 35 kilometers (22 miles) long and 23 kilometers (14 miles) wide.
The capital cities of both the Congo and the Democratic Republic of the Congo are located on the shores of Stanley Pool, and river ferries serve the area.
The lowest point of the country is the Atlantic Ocean coastline (0 m).