A jet propulsion pump (10) for use with watercraft includes a propeller (40) mounted on a shaft (42) for axial rotation, and a pump chamber (20) having a cylindrical inlet (30) and a downwardly inclined outlet (50) connected to an aperture (29) in the pump chamber (20). The propeller (40) is positioned within the cylindrical inlet (30). An outer wall portion (24) of the pump chamber (20) is outwardly spiralling from the cylindrical inlet (30) to assi st flow of fluid entering the pump chamber (20) through the cylindrical inlet (30) and expelling from the pump chamber (20) at the downwardly inclined outlet (50).
