The Sei whale is among the fastest of all cetaceans, and can reach speeds of up to 50 km/h / 31 mph / 27 knots over short distances.
The sei whale (Balaenoptera borealis) is a baleen whale, the third-largest rorqual after the blue whale and the fin whale. It inhabits most oceans and adjoining seas, and prefers deep offshore waters. It avoids polar and tropical waters and semienclosed bodies of water. The sei whale migrates annually from cool and subpolar waters in summer to winter in temperate and subtropical waters, with a lifespan of 70 years.