It's not often you see a fisherman cutting a fish free, but that's exactly what one New Zealand man did after a baby humpback whale became trapped in cray pot lines off the coast of Australia.

Fisherman Joe Brogan, 42, grabbed his knife and jumped right into the water. At first the whale tried to swim away and escape, but Brogan swam even closer, taking direction from his friends on board.

"Cut it closer," the man holding the camera directed. "Don't try and get it off, mate; just cut the line."

Brogan finally cut the rope around the baby whale's tail and set it free. "That's it; go free, baby," one man on board cheered.

Patrick Brogan, Joe's father, told 3 News that his son wouldn't have thought twice about saving the animal.

"If he'd thought about it, he wouldn't have done it," Brogan said. "[He said] it was a wonderful feeling having done that."

Joe Brogan later said on Facebook, "It's the best feeling you will ever have."