Watch this Dizzying Descent Into a 300-Meter-Deep Antarctic Borehole

The recession of Earth’s ice caps is among the most obvious bellwethers of human-driven climate change. Scientists have captured this decades-long trend from space with satellite reconnaissance, but groups like the Aotearoa New Zealand Ross Ice Shelf program are taking a more hands-on approach by studying these extreme environments up-close.

At about the size of France, the Ross shelf is the largest feature of its kind in Antarctica, but not much is known about what lurks beneath its surface. So naturally, the Ross Ice Shelf program, a collaboration between several New Zealand universities and research institutes, melted out a 300-meter-deep borehole into it, and over the past few months, has been probing it for clues about the lower shelf’s response to warming waters.

Thanks to the team’s dizzying camera descents into the borehole, we have footage taken nearly a half-kilometer into the frozen abyss of ice—the shot doesn’t stop even when the lens splashes into the polar ocean. Watch, and be horrified at the prospect of dropping something valuable into this 25-centimeter-wide nightmare tunnel.

The expedition shared some initial findings from the study in an article published by The Conversation, stating that their “new data indicate an ocean warming compared to the measurements taken during the 1970s, especially deeper down.”

It’s unclear how warming waters underneath the Ross ice shelf will impact its long-term “longevity,” the team said. While it is the most gargantuan and stable of all ice shelves in Antarctica, it has been experiencing unusually high melt rates in recent years. Because these ice shelves act as natural buttress for ice contained in sheets on land, their integrity is crucial to holding back the floodgates of ice melt within the continent. If weakened, as has been the case with Antarctica’s Larsen ice shelf, it could exacerbate the global trend of rising seas.

The team’s article comes just a few days after President Trump’s suggestion, during a recent interview with Piers Morgan, that polar sea ice cover are setting “record” highs. As a long-term trend, the opposite is true, and this grim reality has galvanized climate scientists to better understand polar melt and its impact on the global environment. This deep dive into the Ross Ice Shelf is just the latest—and possibly gnarliest—of a worldwide, multipronged approach to quantifying the mechanisms behind these shifts, and assessing their future risks.

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