Abstract: An automatic pool cleaner having a turbine including a housing having a flow chamber and chamber wall with inlet and outlet ports, a rotatably-mounted turbine rotor, and turbine vanes each having a proximal end connected to the rotor and a distal end movable with respect to the rotor between extended positions adjacent to the wall and retracted positions spaced from the wall and closer to the rotor to allow passage of debris pieces of substantial size through the turbine. Some preferred embodiments are: curved vanes; vanes pivotably mounted to the rotor; and an eccentric rotor mount within the turbine chamber. Pivotably-mounted vanes preferably have enlargements at their proximal ends which are freely insertable into cavities in the rotor; most preferably, each vane is symmetrical about a center line such that either end is able to serve as the proximal end in engagement with the rotor.