Mobile nozzles and associated systems for cleaning pools and spas are provided. One or more mobile nozzles traverse a pool or spa, dislodge settled debris from the floors thereof, and direct the debris to one or more outlets for removal and/or filtration. Each of the mobile nozzles can include a body, a water intake, a discharge nozzle configured to expel pressurized water, one or more sensors adapted for navigation and/or to locate debris within the pool or spa, a propulsion system, and a control system including a memory and a processor. The discharge nozzle can be movable between a plurality of orientations relative to the body, or can have a fixed orientation. The processor is operable to identify debris in the pool or spa and cause the discharge nozzle to be positioned such that the pressurized water expelled therethrough directs the debris toward a debris collection zone or outlet.