The High-finned sperm whale is a supposed variant or relative of the known sperm whale that is said to live in the seas around the Shetland Islands in Europe, the Antarctic Ocean, and Nova Scotia. The major difference between this creature and other sperm whales is the presence of a tall dorsal fin on its back, which the known sperm whale, Physeter macrocephalus, lacks. Two such stranded whales were supposedly observed by Sir Robert Sibbald. He described their dorsal fins as being similar to a "mizzen mast".
Although species cannot be given scientific names until a type specimen is discovered, Physeter tursio has been suggested as the High-Finned Sperm Whale's scientific name by an early observer. A possible sighting was off the Annapolis Basin, Nova Scotia, Canada on either August or September 27, 1946. It was apparently trapped there for 2 days. Its length was estimated to be between 10 and 100 feet (About 3 to 30 Meters).