Abstract: A ductless wall thruster for a marine vessel has a housing with a plenum chamber therein and, at a forward end of the housing, at least one inlet opening surrounding an outlet opening. An impeller is rotatably mounted within the housing so that when the impeller is rotated, it draws water into the housing and discharges it through the outlet opening to create a thrust. Preferably, there is a plurality of equally dimensioned inlet openings defined by stationary vanes inclined in a direction opposite the normal direction of rotation of the impeller. The outlet opening is preferably defined on a forward end of a central impeller housing in which the impeller is mounted, with the impeller having a flow area therethrough which is greater than the flow are through the outlet opening.