Abstract: A propulsion device for persons in an upright position in water has a loose flexible panel within a reinforced border; the panel is attached to the frontal lower leg by a knee strap at its top and by ankle and foot straps at its bottom. Walking or striding motions of the wearer's legs cause the material of the panel to billow out and provide resistance against the water when the wearer's leg moves backward, propelling the wearer forward through the water; the panel collapses against the leg and conforms to its shape when the leg is moved forward, offering little or no increased resistance to the water.