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 1800 mm; the beam is at least 800 mm; the deadrise angle at least 3°; and the center of rotation of steering control is located near the halfway distance from transom to bow.