SYDNEY - A man was knocked unconscious and three others suffered facial fractures and broken ribs after a whale slammed into a charter fishing boat off Australia's north coast, the skipper said on Monday.

The nine-meter vessel was returning to port in the Whitsundays off the Queensland state coast with eight passengers on board when a humpback whale rammed it from below, sending it airborne.

"Within a split second we all hit the floor, the boat launched up into the air and it dislodged everyone off their feet," Captain Oliver Galea told AFP of the drama on Saturday. "None of us knew what happened."