The Senegal River rises not very far from the source of the Niger, at the extreme west of the so-called Kong Mountains. It flows first northwest and then west, and loses itself in the Atlantic Ocean a little north of Cape Verd.
The length of the river has been estimated as upwards of eleven hundred miles. The last seven or eight hundred miles are navigable only for flat-bottomed boats. In fact, here and there throughout its whole course, the navigation of the river is frequently interrupted by cataracts, shoals, and rocks.
The banks of the river are covered with verdure, and in some sections with timber. In the lower part of its course the river is dotted with numerous islands. These are usually large, well cultivated, and fertile.
The entrance to the river is somewhat difficult, owing to the breakers and to the existence of a sandbar. In dry weather this bar has been known to be covered by only eight or nine feet of water.
The Gambia is a smaller stream than the Senegal, flowing about in the same direction and through the same section of country. Its length is estimated at about one thousand miles. The mouth of the river is about four miles broad. Just before the river reaches the sea its current is fully double its width at the mouth.
The river is navigable for vessels of one hundred and fifty tons as far as the town of Barraconda. This town is situated on the right bank of the stream, about two hundred miles from the sea. The river enters the sea a little to the south of Cape Verd.
The Senegal and Gambia drain the tract of country named, most appropriately, Senegambia. It is a large maritime tract, bounded on the north and west by the Sahara and the Soudan, on the south by Sierra Leone, and on the west by the Atlantic Ocean.
Between the two rivers, which are two hundred and fifty miles apart, there are no very important water-courses. Between the Gambia and the frontier of Sierra Leone there is but one stream of any size, the Rio Grande.
The coast of Senegambia is deeply indented by various arms of the sea, which resemble somewhat the estuaries of rivers.
The country forms the western and northern slope of the Kong plateau. Portions of it are still but partially explored.