Scientists and explorers take a number of risks when they travel to Antarctica. One of the more macabre gambles is that they'll perish during their mission, and their bodies will never be recovered. According to the BBC, hundreds of frozen corpses may be trapped beneath layers and layers of Antarctic snow and ice.

“Some are discovered decades or more than a century later,” Martha Henriques writes for the BBC series Frozen Continent. “But many that were lost will never be found, buried so deep in ice sheets or crevasses that they will never emerge—or they are headed out towards the sea within creeping glaciers and calving ice.”

In the world’s most extreme regions, this is not uncommon. For comparison, some estimates suggest that more than 200 bodies remain on Mt. Everest. Antarctica's icy terrain is rugged and dangerous. Massive crevasses—some concealed by snow—measure hundreds of feet deep and pose a particularly serious threat for anyone crossing them on foot or by dogsled. There’s also the extreme weather: Antarctica is the coldest, driest, and windiest place on Earth, yet scientists recently discovered hundreds of mummified penguins that they believe died centuries ago from unusually heavy snow and rain.

One of the most famous cases of a left-behind body on Antarctica dates back to the British Antarctic Expedition (also known as the Terra Nova Expedition) of 1910 to 1913. British explorer Robert Falcon Scott and his four-man team hoped to be the first ones to reach the South Pole in 1912, but were bitterly disappointed when they arrived and learned that the Norwegian explorer Roald Amundsen had beaten them to it.

On the return trip, Scott and his companions died of exposure and starvation while trapped by a blizzard in their tent, just 11 miles from a food depot. Two of those bodies were never found, but the others (including Scott’s) were located a few months after their deaths. Members of the search party covered their bodies in the tent with snow and left them there. The bodies have since travelled miles from their original location, as the ice grows and shifts around them.

Other evidence suggests people landed on Antarctica decades before Scott’s team did. A 175-year-old human skull and femur found on Antarctica’s Livingston Island were identified as the remains of a young indigenous Chilean woman. No one yet knows how she got there.

Accidents still happen: After coming close to completing the first solo, unaided traverse of Antarctica, British adventurer Henry Worsley died of organ failure following an airlift from the continent in 2016. Most modern-day polar visitors, however, have learned from past missteps.

[h/t BBC]