The blue whale is a marine mammal belonging to the suborder of baleen whales (called Mysticeti). At up to 32.9 metres (108 ft) in length and 172 metric tons (190 short tons) or more in weight, it is the largest animal ever to have existed.

Blue whales can reach speeds of 50 kilometres per hour (31 mph) over short bursts, usually when interacting with other whales, but 20 kilometres per hour (12 mph) is a more typical traveling speed. When feeding, they slow down to 5 kilometres per hour (3.1 mph).