23. Humpback whale slapping its pectoral fins, typically one-third the length of its body. Flipper slaps are often seen in surface active groups battling for access to a female. These fins are proportionally the longest of any cetacean and it’s been suggested they have evolved to give them better manoeuvrability and increased surface area for temperature control during their migration across warm & cold waters.

Humpback Whale, Tonga