The beluga whale was a species of sentient cetacean native to the Arctic oceans of Earth. They had their own spoken language. They greatly enjoyed swimming with humanoids and would encourage it whenever possible.
By the late 24th century, beluga whales were serving as navigators in Cetacean Ops on Federation starships. Two such Starfleet officers, Lieutenants junior grade Kimolu and Matt, were assigned to the USS Cerritos in 2381. (LD: "First First Contact")