A humpback whale spared from almost certain death by three men off the coast of California seemed to repay the favour to its rescuers with a fabulous display of breaches and dives.
The hour-long performance was caught on camera just moments after the creature was cut free from fishing nets.
When the boat came across the whale it was trapped with its tail and flippers entangled in the nets.
The whale watchers first thought the humpback was already dead as it was floating on top of the water. But then it let out a loud breath through its blow hole.
Michael Fishbach, co-founder of the Great Whale Conservancy, decided the best thing to do was to get into the water and snorkel alongside it.
He said: "As I swam alongside the animal our eyes met.
"There were no words we could share but I wanted to let the whale know that we were there to help.
"It took some effort to stay focused given the great emotion of the moment.
"The sight of this large and beautiful creature trapped and so close to death was almost overwhelming.
"I must admit I was a bit scared because I knew the whale was frightened and fatigued but could still kill me with one panicked movement."
He said the whale"s tail was entangled in so uch gear that it was weighed down by about 15ft.
Michael got back on the boat to radio for help, but no one could reach them on time, so they tried to cut the net off the whale with a small knife.
The three men managed to free one of the fins but the whale sensed a "spark of freedom" and swam away, pulling the boat with it. But it then surfaced again and, after about half an hour of working, the whale was totally free.
For the next hour they watched the whale breach around 40 times and then dive down waving its tail above the water.
Michael said: "We all believed it was at least a show of pure joy, if not thanks.
"We were all proud and thrilled that we saved this fantastic young life.
"It was an incredible experience that none of us will ever forget."
On the video a little girl can be heard saying: "I know what she is doing. She is showing us that she is free.
Her mother replies to her: "I think she is showing us a thank you dance."
Maybe it was a "thank you dance", maybe it wasn"t - but it"s certainly nice to believe it, and a magical thing to watch :