PURPOSE: To enable a swimmer to be propelled under water in any direction with any speed by providing a submarine pump, at least one nozzle connected to the pump to jet water, a device for adjusting water flow to the nozzle and further a nozzle mounting angle changer.

CONSTITUTION: This propeller introduces water from the bottom of a submarine pump 2 driven by a battery 3 and jets the water from a nozzle 5 through a water conduit 5 to generate a thrust. A swimmer puts the side of the propeller opposite to the nozzle side on his back and carries the propeller on his back by means of a fixture to advance with the reaction of jet as a thrust. Also, the vertical and horizontal directions of the thrust are changed by operating a nozzle direction guide 6 with electric power from the battery to change a nozzle mounting angle, and the propelling angle is changed by adjusting flow from the submarine pump. Both propelling direction and speed are changed by the swimmer's operation of a switch. When the moving range of the swimmer is limited, electric power in place of the battery may be supplied from on the ground through a wire to drive the pump and nozzle.