In the video, you can see a bottlenose dolphin approach a diver who noticed his fin was entangled in fishing line.
The diver used a knife to cut away at the line, freeing the dolphin.
The group was on a night dive to view manta rays off the coast of Kona, Hawaii.
They say they've helped free manta rays from entanglement before and that the dolphin showed interest in getting some help for himself.
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