Blue whales can swim fast, with burst up to 20 knots. Long and streamlined, they are capable of sustaining speeds of 5 to 10 knots while traveling or foraging for food. Enormous muscles in a blue whale's caudal flanks and peduncle power its wide flukes up and down.
Blue whale fluking up (raising its tail) before a dive to forage for krill, Baja California (Mexico).