Two divers encountered a 26ft long deep-sea worm off the coast of Whakaari in New Zealand.
The creature is thought to be a Pyrosome, a huge hollow colony made up of thousands of individual organisms.
Diver Andrew Buttle, 48, said: “Having never seen one in person or even footage or photos of one before, I was quite incredulous and elated that such a creature existed.
“It was very puzzling but also fantastic to be able to view it right up close and spend so much time with it.
“The island is 48 kilometres from the mainland, and there is a vast amount of fish life and nutrients in the water that may have had the right circumstances to become so large.”