The divers were on a Manta Ray dive at night in Hawaii when they spotted the dolphin swimming with the rays.
"I noticed he had a fishing wire wrapped around his left fin," Keller Laros said.
Laros watched as the mammal swam by a few times, and then he did something unusual.
"I reached out with my left hand and gestured with my index finger 'Come here.' And he swam right up to me," he told KFMB.
"The fact that he seemed to recognize my gesture, that blew me away," he said, shaking his head.
Then the dolphin did something even more remarkable. “He put himself in the position to allow me to most effectively remove the hook and the line,'” Laros went on.
The animal even went to the surface for air once during the “procedure,” but came right back to allow Laros to finish.
After a dive knife was used to cut the line away, the dolphin swam off.
Laros remains stunned and impressed by what the creature did. "That was just amazing, to think that animal is that smart," he finished.
Watch the video below.