The dolphin needed help - and without saying so in words, it asked for it.
Professor of Psychology at Hunter College Diane Reiss says it's conceivable and possible that the dolphin was looking for help.
"[Dolphins] have the cognitive ability to do that, whether that's what this dolphin is actually doing, we can't say for sure, but it certainly looks that way to me," Reiss tells Seattle's Morning News.
It started when a group was out diving off the shores of Hawaii's mainland. The dolphin approached and the diver motioned for it to come over, and it did. It was tangled in a line and the animal positioned itself so the diver could untangle it.
At one point, you can see the dolphin go up for air, and come back down so the diver can finish assisting him.
"What's amazing to me is seeing the calmness and the stillness that the dolphin showed in positioning and repositioning towards the diver," says Reiss. "It looks like [the dolphin] seems to understand that it's being helped."
Reiss says dolphins are smart. Their brains are big, and complex - packed with neurons much like our brains. Dolphins show complexity in their social interaction, they help each other in foraging and mating in various kinds of activities.
What's really compelling, says Reiss, is that for years there have been reports about humans being saved by dolphins. There are old Greek tales of dolphins saving humans, as well as modern day stories of dolphins coming to the aid of humans.
"The modern stories that are told seem to be indicative of the dolphins understanding something about the plight of others. What's lovely about this story," she says, "is evidence of a dolphin understanding its own plight."