Mariental lies on the B1 national road 232 kilometres north of Keetmanshoop and 274 kilometres southeast of Windhoek. The town and the surrounding area are in a hot, arid region.
The town lies near the Hardap Dam, the largest reservoir in Namibia. It supplies the city with water and controls the flow of the Fish River which flows in a southerly direction past the town.
The dam provides water for irrigation, making possible to cultivate animal fodder, as well as corn, fruits and vegetables. The town is surrounded by flourishing commercial farms which focus on game farming as well as sheep and ostrich farming. Cattle farming also remains popular in the region. Export grapes, cotton lucern and dairy farming is also sustained by irrigation from the dam.
Mariental boasts some of the best safari and hunting experiences in Namibia at lodges like Lapa Lange and Anib Lodge.