A portable water level-responsive mooring device has a mooring strap with a ring capable of engaging the mooring device around a dock piling. The mooring strap has a suitable length of cord having a clip or ring on each end capable of releasably attaching to a fender, spacing tubes, and rollers. The spacing tubes and rollers have an outer diameter greater than the outer diameter of the spacing tubes and an inner diameter larger than the outer diameter of the cord. The cord is positioned within an arrangement of the spacing tubes and rollers, the length of cord being sufficient to wrap around a dock piling.