Its total length is 642 km (399 mi), rising in the Drakensberg Mountains on the Lesotho border, flowing southwestward and then westward before joining the Orange River near Bethulie in the southern Free State.

The river was originally named Prinses Wilhelminas Rivier in 1777, by Colonel R J Gordon.

[1] The origin of the River Caledon is in the former bantustan of QwaQwa, near the border with Lesotho, southwest of Witsieshoek.

It then flows south-west bordering Lesotho's capital city, Maseru.

Its total length is about 480 km (300 mi), and its valley experiences great temperature swings.