An amphibious vehicle has retractable wheels (2, 3) attached to hubs (2), and a planing hull (10, 11, 3). Front wheels are arranged to be steered by a power assisted transversely mounted element (16), which may be a rack and pinion unit. The element may be linked to the wheels by links (14, 14′), which fold up to position (14″) when the wheels are retracted. Actuating rod (28) is mounted to said element, and arranged for transverse movement. A flexible coupling means, such as cable (34) and sleeve (36), connects rod (28) to a steerable part (42, 4) of a marine propulsion unit, to effect marine steering. Road and marine steering may be operable simultaneously. More than one front steered axle, and/or marine propulsion unit, may be fitted. The steering system is readily adapted to all kinds of power assisted steering, and also to “steer by wire”.