These two kayakers got more than they bargained for on a trip to spot sea turtles off the Hawaiian island of Maui - winding up in the path of an anxious female humpback whale, surging out of the water to protect her young.

The female adult flapped her fin at the passers-by to warn them off, before coming up out of the water as the kayakers quickly escaped. Neither was hurt.

Humpback whales are not aggressive, but adults can reach up to 16 metres in length and 36,000 kilos in weight.

About 60 per cent of the population of North Pacific humpback whales migrates to Hawaii every winter to mate and to give birth to calves conceived during last year's breeding season.

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