A pontoon houseboat is a boat with living quarters that is constructed on pontoons. A pontoon is a watertight vessel that is used for supporting boats, bridges or boat docks. Pontoons are most commonly cylindrical and made of marine-grade aluminum.
Small houseboats are constructed using two pontoons. Larger houseboats are constructed using three pontoons. Pontoons are cylindrical in shape and are used to construct houseboats by orienting the pontoon so that the circular face of the pontoon faces toward the front of the vessel. In the case of a larger houseboat, a third pontoon might be added to the structure to help support the additional weight.