 Whales have two flippers on the front , and a tail fin . These flippers contain four digits . Although whales do not possess fully developed hind limbs , some , such as the sperm whale and bowhead whale , possess discrete rudimentary appendages , which may contain feet and digits . Whales are fast swimmers in comparison to seals , which typically cruise at 5 – 15 kn , or 9 – 28 kilometres per hour ( 5 @.@ 6 – 17 @.@ 4 mph ) ; the fin whale , in comparison , can travel at speeds up to 47 kilometres per hour ( 29 mph ) and the sperm whale can reach speeds of 35 kilometres per hour ( 22 mph ) . The fusing of the neck vertebrae , while increasing stability when swimming at high speeds , decreases flexibility ; whales are unable to turn their heads . When swimming , whales rely on their tail fin propel them through the water . Flipper movement is continuous . Whales swim by moving their tail fin and lower body up and down , propelling themselves through vertical movement , while their flippers are mainly used for steering . Some species log out of the water , which may allow then to travel faster . Their skeletal anatomy allows them to be fast swimmers . Most species have a dorsal fin . 
