Abstract: A contra-rotating compressor includes a first shaft assembly disposed in a housing, the first shaft assembly including an outer shaft, and a first plurality of impellers coupled to the outer shaft, wherein the outer shaft includes a final stage that includes a final impeller of the first plurality of impellers, a second shaft assembly disposed in the housing and rotatable about the longitudinal axis, the second shaft assembly including a second plurality of impellers, a first pair of annular seals between the final stage and an inner surface of the housing, the pair of annular seals being configured to permit relative rotation between the final stage and the housing, and a third annular seal positioned between the outer surface of the final stage and an inner surface of the second shaft assembly, the third annular seal configured to permit contra-rotation between the final stage and the second shaft assembly.