Abstract: A device for use in activity on snow-covered surfaces, water or the like having a bottom board (1) for contact with the surface, longitudinal steering ribs on the underside and with upwardly curved faces at the front edge and preferably also at the rear edge. A top board (2) is adapted to the user and his position of use by the formation of well-like depressions along the side areas for the user's legs. On the top board (2) in the central region there is formed an elongate, trough-shaped depression (6) in which there is secured an airtight bag (3) that is adapted to the depression. The central portion (10) of the bottom board has at least one, preferably two central steering ribs/grooves (12). The front is equipped with fastening means (8) for a towing line or rope (17).