A pontoon boat is provided with a jet drive propulsion system in which an impeller is driven by an engine. The jet drive propulsion device is dirigible as a result of the fact that a nozzle of the device is rotatable about a generally vertical steering axis. The jet drive device can be supported below a deck of a pontoon boat and located between two flotation tubes of the pontoon boat. Alternative locations can also be used, such as within the structure of the flotation tubes themselves.