Abstract: A conventional bicycle has its frame rigidly supported by a base framework held by adjustable length outrigger arms, whose outer ends are connected with bearings mounted on two spaced floats. The rear bicycle traction wheel frictionally engages and drives a propulsion wheel connected through gearing with a propeller. A tubular arm pivoted at its forward end to the base framework extends rearwardly beneath the bicycle traction wheel and supports the propulsion wheel, gearing and propeller. A pivoted rudder on the rear end of tubular arm is operated by cables extending through such arm and leading to the axle of the front steering wheel of the bicycle. The device possesses windsurfing and rowing capabilities.