In 2021, a team drilling for sediment samples on the Filchner-Ronne Ice Shelf in Antarctica made an unexpected biological discovery. The researchers, who were focused on geological work rather than marine biology, lowered a camera into a borehole and found a boulder on the seafloor covered with living animals, including sponges and other stationary organisms. The location was roughly 260 kilometers from the nearest open water, in complete darkness and water temperatures near minus 2.2 degrees Celsius. This finding contradicted the long-standing assumption that permanent animal life could not survive that far from sunlight and food sources.

For decades, the prevailing theory among ocean scientists was that life becomes scarcer with distance from open water and sunlight. Antarctic ice shelves extend for hundreds of kilometers over the ocean, and the water beneath them never receives daylight. Photosynthesis requires light, so most researchers expected the deep water under these shelves to be nearly empty, perhaps containing only mobile scavengers that had drifted in from other areas. This theory remained largely unchallenged because testing it directly required drilling through ice that is hundreds of meters thick, a process that demands weeks of preparation and hot water to melt the borehole. Before 2021, only a handful of boreholes had been drilled deep enough to test the idea, and most had shown only scattered mobile animals.

The 2021 discovery, led by researcher James Smith and later studied by marine biologist Huw Griffiths of the British Antarctic Survey, was the first to find stationary animals that far from light. The creatures, which included at least two kinds of sponge and possibly tube worms or stalked barnacles, do not swim to find food. They wait for organic material to drift down to them, potentially from as far as 1,500 kilometers away, carried by deep ocean currents over months or years. Because the borehole sealed shut within hours of drilling, scientists could not run DNA tests or determine the age of the animals or their exact food sources. The specific spot has not been revisited since.

This was not the first time an Antarctic drilling project uncovered something unexpected. Nearly a decade earlier, a different group spent over two decades drilling toward Lake Vostok, the largest known subglacial lake in Antarctica. Located beneath roughly 4 kilometers of East Antarctic ice, Lake Vostok is close in size to Lake Ontario and has been isolated from the surface for an estimated 15 million years. Scientists have mapped close to 400 subglacial lakes under the Antarctic ice sheet, with Vostok being the largest. Russian scientists began drilling toward the lake in 1989 from Vostok Station, which holds the record for the coldest natural temperature ever measured on Earth, close to minus 89 degrees Celsius in 1983.

The drilling progressed slowly, partly because the ice cores themselves were scientifically valuable, containing trapped air bubbles that record the planet’s climate over 400,000 years. The team broke through to the lake surface in February 2012. However, the results were complicated by contamination from the drilling fluid, which contained surface bacteria. The Russian team did not follow the strict decontamination protocols used by other countries’ research programs, making it difficult to confirm whether any organisms found in the samples came from the lake itself. To date, no native life has been verified from Lake Vostok.

The mission nonetheless has broader significance. Jupiter’s moon Europa and Saturn’s moon Enceladus are both believed to hold oceans of liquid water sealed under thick ice. Developing methods to safely explore a lake buried under kilometers of Antarctic ice is considered practical preparation for searching those distant oceans.

A different Antarctic lake, drilled a year earlier with cleaner methods, provided clearer results. In January 2013, the WISSARD project, short for Whillans Ice Stream Subglacial Access Research Drilling, became the first to successfully and cleanly sample an Antarctic subglacial lake. Their target was Lake Whillans, located under about 800 meters of ice in West Antarctica. The team used a custom hot water drill designed to filter and treat its own water, reducing the risk of contamination. The samples contained close to 4,000 distinct types of microbes living in a lake with no sunlight. These chemosynthetic organisms do not draw energy from the sun; instead, they pull energy from minerals dissolved in the water, such as iron, nitrogen compounds, and sulfur.

Later research led by scientist Trista Vick Majors found that these microbes were actively changing the chemistry of the lake, breaking down organic material and functioning as a nutrient recycling system in total darkness. Lead researcher John Priscu described the discovery as clear proof that the lake harbors life. Follow-up studies confirmed that the ecosystem was active, and the team returned a year later to sample a different location.

In 2015, engineers from Georgia Tech built a torpedo-shaped robot called IceFin, designed to be lowered through a narrow borehole and swim freely under the ice. Its first deep dive took it to the seafloor beneath the Ross Ice Shelf, roughly 500 meters down, where cameras recorded a seafloor covered in sea stars, sponges, and anemones. The robot, about 4 meters long and less than 30 centimeters across, can pass through a hole barely wider than a dinner plate.

Five years later, IceFin returned to explore the grounding zone under Thwaites Glacier in West Antarctica. Robot engineer Britney Schmidt and her team lowered the robot through a borehole roughly 700 meters deep. As it moved along the ice ceiling above the seafloor, its lights revealed tentacled sea anemones burrowed upside down into holes in the ice, hanging from the ceiling rather than growing from the ground. As the robot approached, the anemones retreated into their burrows one by one.

In 2017, a different kind of discovery came when a chunk of ice known as A68 broke away from the Larsen C ice shelf. The iceberg, covering close to 5,800 square kilometers, exposed a stretch of seafloor that had been sealed under roughly 200 meters of ice. Years later, researchers sent a remotely operated vehicle down into the newly uncovered area, originally hoping to study the retreating ice shelf and search for traces of Shackleton’s lost ship Endurance. Instead, they found more than a thousand circular nests arranged in patterns across the seafloor, each built and guarded by a small Antarctic ice fish known as the yellowfin notothen. Every nest had been maintained by a parent fish standing guard over its eggs in an area that had been completely sealed off from outside observers.

Collectively, these findings point to a more complex picture of life beneath Antarctic ice than previously understood. Sponges survive far from food sources, microbes run on minerals instead of sunlight, anemones have moved into the ice itself, and a fish nursery remained hidden for years until an iceberg broke free. What connects these stories is how difficult it is to go back. The Filchner-Ronne borehole sealed shut within hours. Lake Vostok took two decades to reach once, and contamination still leaves the answer unresolved. IceFin depends on a hole that stays open only briefly before the cold seals it shut. Less than a quarter of the ocean floor has been mapped, and the ice above Antarctica continues to reveal that there is more life down there than anyone expected.