The old folk wisdom used to be that fish couldn’t swim backward. We’ve known for a while that isn’t true. Fish can reverse direction when they need to reposition themselves or squeeze through tight spaces. But researchers studying a fjord in Greenland recently captured footage of a fish just casually drifting backward.

The footage came from a new PLOS One study conducted in Inglefield Bredning, a glacial fjord in northwest Greenland. Scientists lowered a camera and hydrophone 853 feet beneath the surface to study one of the least observed ecosystems on Earth. They used red LED lights so as not to disrupt marine life.

For the next three days, the camera would record 10-minute clips every 20 minutes while the hydrophones listened for underwater activity. They recorded 223 video files showing all sorts of deep-sea wonders, like jellyfish, shrimp, bristle worms, and copepods. All fascinating in their own right, but one clip stood out from the bunch.

A passing snailfish curled its tail upward and slowly drifted backward with the current before hovering motionless for about 16 seconds and disappearing out of view. Podolskiy later described it to Discover Magazine as a “relaxed fish drifting backward,” adding, “I do not want to insult any fish, but seemingly there is little to do down there.”

When you’re buried that deep below a giant glacier, what else is there to do but entertain yourself by swimming backward?

The hydrophones also picked up narwhal calls almost every day, though the whales mostly ignored the equipment, which means the purposely indistinct equipment did its job.