A planing amphibious vehicle with retractable wheels and a sit-astride seat having dimensions that impart enhanced capability in both land as well as water modes of operation. The beam, track, dead rise angle and the location of the handlebars cooperate to enhance freeboard and ground clearance without sacrificing manoeuvrability. The length is at least 2400 mm; the beam is at least 1250 mm; the deadrise angle at least 10.degree.; and the handlebars are located only slightly forward of the halfway distance from transom to bow.