This group of tourists off the coast of Greenland witnessed a rare sight on their water safari: a sleeping whale.

The clip, filmed August 9, shows a 16m-long humpback whale grabbing 40 winks before the boat's engine startles the mammal and wakes it up.

"I was guiding a whale safari from Ilulissat [a coastal town in western Greenland]. Then we saw this 16m-long humpback whale sleeping, so we went closer to it and it woke up when we turned the engine on," filmer Malik told Newsflare.