Whale swimming backstroke off East Coast Australia 

This male whale is using both pectoral fins to attract attention from other whales by slapping them on the ocean surface.
It is peak north migration of humpback whales off the east coast of Australia. So many whales around at the moment.
Adult whales are 30% longer than the boat, making these encounters truly impressive. For reference, a waving fin is 5m / 15feet long.