The Mzimkhulu River (also spelled Umzimkulu or uMzimkhulu) is a river in KwaZulu-Natal, South Africa, rising in the Drakensberg mountains just north of Rhino Peak near the Lesotho border and flowing southeast to enter the Indian Ocean through an estuary at Port Shepstone. The river passes through towns including Underberg and Umzimkhulu along its course.

For paddlers, the river is generally rated Class 2-3, with a few Class 4 rapids appearing at certain points or water levels. This range makes it accessible to intermediate paddlers while still offering technical challenge, particularly when water levels are elevated. Commercial whitewater rafting operations run on the river, reflecting its suitability for guided group trips as well as independent paddling.

The Mzimkhulu is recognized as one of KwaZulu-Natal's established canoeing and kayaking destinations. In late February each year, the river hosts the Drak Challenge, described as one of South Africa's most popular canoe races, which draws significant paddling interest to the region around that time of year.

Access points, facilities, and seasonal water conditions are not well documented in general resources, so paddlers planning a trip are advised to contact local outfitters or race organizers for current logistical information, particularly regarding put-in and take-out locations and water levels at different times of year.