Several species of whale (e,g. Right whales and Humpback whales) have developed a behaviour called 'Tail Sailing' in which the whale lifts its tail into the air and maintains the position for long periods.

It's not known why they do this. Current theories include :

• Gaining 'free' movement from wind energy
• For cooling
• To enable feeding in shallow water
• Communication of some kind

Further details (with photo) Whale Coast Route