The 52-hertz whale is an individual whale of unidentified species, which calls at the very unusual frequency of 52 Hz. This pitch is a much higher frequency than that of the other whale species with migration patterns most closely resembling this whale's. It has been detected regularly in many locations since the late 1980s and appears to be the only individual emitting a whale call at this frequency. It has been described as the "world's loneliest whale".