Abstract: A water bicycle comprising two relatively parallel, elongated floating bodies and a frame supported by said floating bodies provided with a seat whereby each of the floating bodies is provided with a frame part supported by the associated floating body and a spacing member is releasably arranged between the two frame parts for maintaining the frame parts at a given distance from the other and the floating bodies connected therewith, the seat being supported by an auxiliary frame provided with two guides cooperating with guides forming part of the frame parts on the floating bodies so that in the longitudinal direction of the floating bodies the guide parts are slidable over or in one another, while bolt are provided for fixing the guides in a desired position relative to one another.