Guinea shares a border with Guinea-Bissau to the north-west, Senegal to the north, Mali to the north-east, Ivory Coast to the east, Sierra Leone to the south-west and Liberia to the south. The nation forms a crescent as it curves from its southeast region to the north and west, to its northwest border with Guinea-Bissau and southwestern coast on the Atlantic Ocean. The sources of the Niger River, the Gambia River, and the Senegal River are all found in the Guinea Highlands.