Flight instructor Gerry Charlebois says the 50-foot whale was bent in half and appeared to have suffered blunt force trauma to its side.
The owner of the Birds in Paradise Flight School told The Garden Island newspaper Monday it was one of the most disturbing sights he's ever seen while photographing whales.
Ed Lyman of the Hawaiian Islands Humpback Whale National Marine Sanctuary says it's not clear if the whale has a broken back.
After looking at Charlebois' photos, Lyman says the whale was injured between its dorsal fin and tail.
Information from: The Garden Island, http://thegardenisland.com/