A drive shaft and improved marine water pump are disclosed. The drive shaft connects to a water pump impeller on one end and to a an accessory drive for rotating the impeller on the opposite end. The drive shaft of the present invention comprises an elongate shaft portion that includes differing sectional diameters to facilitate easy placement of the pump shaft within the marine water pump and through the marine pump bearing assembly preventing bearing assembly oil seal damage. The drive shaft further comprises a widened drive shaft tang to facilitate more secure engagement to a marine pump accessory drive and a flange rim adjacent to the pump shaft tang for improved and quicker alignment of the marine pump shaft with respect to the marine pump bearing assembly.