A cool video has emerged of a humpback whale breaching out of the water in off the coast of Dalvik in Iceland.

The footage, shot on September 17, shows the whale jumping metres above the surface as whale-watchers gathered for a birthday party.

"Larus Anton, son of the whale watching captain Freyr Antonsson, was celebrating his 12th birthday with his friends on a rib boat when a humpback whale party crashed it," the filmer wrote online.