A screw drive vehicle has a main housing with forward and aft ends and first and second lateral sides. A first support arm rotatably supports a first pontoon assembly from the first lateral side of the main housing. A second support arm rotatably supports a second pontoon assembly from the second lateral side of the main housing. A reversible motor in the housing simultaneously rotates the support arms from positions parallel to one another and the main housing to non-parallel positions. Each pontoon assembly includes a tubular housing with exterior screw thread supported for rotation between distal ends of the arm and a reversible pontoon drive motor operably coupled with the tubular housing so as to rotate the housing and thread in a selected rotational direction.