Watercraft with a solid hull and a solid outer side, where a recess extending essentially in a horizontal plane is formed in the outer side of said watercraft above the water line, in which recess an elastically deformable safety element is permanently installed, which element is folded onto itself in a first operating state and is inflated by means of a pressurized fluid from a source of pressurized fluid in a second operating state, characterized in that at least one undercut projection is formed in the recess in the outer side of the watercraft, and in that the safety element has at least one concavity designed as the negative of the positive shape of the projection, so that the projection engages positively and nonpositively with the concavity.