Embodiments of the present invention are directed to devices adapted to enhance propulsion (i.e., propulsion enhancing devices) of watercraft such as, for example, personal watercraft and the like. To this end, a propulsion enhancing device in accordance with the disclosures made herein may be attached to or integral with (e.g., formed unitarily with a housing thereof) a propulsion unit of a watercraft. The propulsion unit generates a stream of water that provides for propulsion of the watercraft. A propulsion enhancing device in accordance with the disclosures made herein includes internal structures that enhance velocity and/or volumetric attributes of a stream of water generated by the propulsion unit by transforming non rotational flow at the inlet of the propulsion enhancing device to rotational flow at the outlet of the propulsion enhancing device.