Jachthaven De Mars is a combined campsite and marina situated within the 400-hectare recreation area of Rhederlaag, near the village of Lathum in Gelderland.

The facility sits in open connection with the IJssel and features two harbors: the larger Oosthaven to the east, which includes visitor berths, a toilet block with showers, laundry facilities, and the harbor office; and the smaller Westhaven to the west, fully renovated in 2020.

The surrounding waters offer opportunities for swimming, fishing, surfing, and sailing. The location also serves as a good base for cycling and hiking, with ferry access across the IJssel providing a direct route to the Posbank.

Nearby destinations include Arnhem, Doesburg, and Doetinchem.