Onseepkans is a small settlement on the banks of the Orange River in the Northern Cape Province, South Africa. It is a border post with Namibia for traffic between Pofadder in South Africa and Keetmanshoop in Namibia. The name, translated literally from Afrikaans, means "(an) opportunity to rinse (off) soap".

Onseepkans was established in approximately 1916 by missionary settlers and relies today on the irrigated lands which are supplied with water from the Orange River. In recent years, table grape farming for export has become the leading type of agriculture in the area.

Onseepkans is the entry point for visits to the Ritchie Falls, the second highest waterfall on the Orange River, after the Augrabies Falls. The Ritchie Falls are in a pristine wilderness area, only accessible after a two day hike or by rafting down from Onseepkans.

There are small communities on both sides of the Orange River in one of the most remote and beautiful parts of the country. The Quiver tree (Kokerboom in Afrikaans) forest between Pofadder and Onseepkans is stunning and is the largest forest of its type in the Southern Hemisphere. It is undoubtedly one of the natural highlights in the area which is dominated by the stark desert landscape and unusual granite outcrops.

The area’s weather is generally very hot. Summer temperatures can exceed 50 °C while in the middle of winter temperatures in the high 30's can still be experienced.

There are about 2000 people living in the area.