An immersion lithography system that compensating for any displacement of the optical caused by the immersion fluid. The system includes an optical assembly (14) to project an image defined by the reticle (12) onto the wafer (20). The optical assembly includes a final optical element (16) spaced from the wafer by a gap (24). An immersion element (22) is provided to supply an immersion fluid into the gap and to recover any immersion fluid that escapes the gap. A fluid compensation system is provided for the force on the final optical element of the optical assembly caused by pressure variations of the immersion fluid. The resulting force created by the varying pressure may cause final optical element to become displaced. The fluid compensation system is configured to provide a substantially equal, but opposite force on the optical assembly, to prevent the displacement of the final optical element.