What Are the Mysterious "Anomalies" Found Under Antarctic Ice?

Background

Roughly 98 percent of Antarctica lies buried under an ice sheet that reaches nearly five kilometres thick in places, which means almost everything known about the ground and ocean beneath it comes from indirect measurement rather than direct observation. Gravity-sensing satellites, ice-penetrating radar, seismic surveys, and, most recently, models that read the subtle way surface ice ripples as it flows over buried obstacles, are the primary tools glaciologists use to reconstruct what lies below. That indirect method is exactly what makes the subject fertile ground for two very different kinds of "anomaly" story: genuine, still-debated geophysical findings on one hand, and viral misreadings of ordinary bedrock data on the other. The four cases below, a disputed gravity anomaly, a buried mountain range, a vanishing hole in the sea ice, and a network of hidden lakes, represent the real science; the "lost city" claims examined further down represent the second kind.

The Wilkes Land Gravity Anomaly

In 1962, American researcher Richard Schmidt first proposed that a large impact crater might lie beneath East Antarctica's Wilkes Land, based on seismic and gravity readings taken during an overland traverse the previous year. The idea resurfaced in far sharper form in 2006, when researchers led by Ralph von Frese and Laramie Potts used data from NASA's GRACE satellite gravity mission to identify a positive gravity signal, a mass concentration or "mascon," centred at roughly 70°S, 120°E and consistent with a buried structure some 480 kilometres across, more than two and a half times the width of the 180-kilometre Chicxulub crater linked to the dinosaurs' extinction.

The impact hypothesis holds that a large asteroid, estimated at four to five times wider than the Chicxulub impactor, struck the region less than 500 million years ago, thinning the crust and leaving a rebounded mantle "plug" beneath the resulting basin. Some proponents have speculated a link to the Permian-Triassic mass extinction roughly 252 million years ago, though this dating remains highly uncertain. Set against this is an alternative, mantle-plume explanation: the same gravity signal, proponents of this view argue, could equally reflect large-scale volcanic upwelling from deep in the mantle rather than an impact at all. Because the site lies under thick ice, no physical rock sample has ever been recovered to test either idea directly, and researchers examining Permian-Triassic boundary rock exposed elsewhere in Antarctica have found no matching layer of impact ejecta, a gap some geophysicists cite as evidence against the impact reading. The anomaly's origin remains a genuinely open, actively studied question rather than a settled scientific fact in either direction.

The Gamburtsev Mountains: Antarctica's Buried Alps

Soviet scientists first detected an unexpected range of mountains beneath East Antarctica during seismic surveys in 1958, but the Gamburtsev Subglacial Mountains stayed largely unexplored for the next half-century simply because reaching them meant flying instruments over some of the most remote ice on Earth. That changed during the 2007-09 International Polar Year, when a seven-nation research team used twin ice-penetrating radar, gravity, and magnetic surveys to map the range from the air. What they found was an Alpine-scale mountain system, peaks reaching roughly 3,000 metres, buried under as much as 4,800 metres of ice, comparable in scale and shape to the European Alps despite lying at the heart of one of the coldest, driest places on the planet.

A 2011 analysis of that survey data traced the range's origin back more than 500 million years, to the collision of ancient continental masses that formed the supercontinent Gondwana; the same rift system responsible for the mountains closely resembles East Africa's modern rift valley and cradles several of Antarctica's largest subglacial lakes. The Gamburtsevs are now understood as the likely birthplace of the East Antarctic Ice Sheet itself: their elevation gave the first ice enough of a foothold to begin accumulating and spreading outward roughly 34 million years ago, during a period when much of the surrounding land was still covered in rivers and forest, a landscape a 2025 radar survey found remarkably preserved beneath the ice in nearby Wilkes Land.

The Maud Rise Polynya: A Vanishing Hole in the Sea Ice

A polynya is an area of open water that persists within an otherwise unbroken expanse of sea ice, and the Weddell Sea has produced one of the most striking examples ever recorded. Satellites first spotted a large polynya over the submerged Maud Rise seamount in the mid-1970s, but nothing comparable reappeared for four decades until the austral winters of 2016 and 2017, when a new Maud Rise polynya opened and expanded from roughly 9,500 square kilometres in mid-September to about 80,000 square kilometres by late October, an area comparable to Switzerland.

A 2024 study explained the mechanism: an unusually strong Weddell Gyre, the great circular ocean current that dominates the region, drove warmer, saltier deep water up and over the Maud Rise seamount and toward the surface, melting sea ice from below and preventing it from refreezing through the winter. The polynya has not reopened at that scale since 2017, and researchers continue to monitor whether it represents an isolated event or a recurring feature that could become more common as the Southern Ocean warms.

Hundreds of Hidden Lakes Beneath the Ice

Antarctica's ice sheet also conceals an extensive network of subglacial lakes, kept liquid by geothermal heat and the immense pressure of the ice above despite surface temperatures far below freezing. A comprehensive scientific inventory has catalogued more than 675 of them, and later satellite surveys using radar altimetry have continued to add more as detection techniques improve. Most are small and have never been directly sampled; scientists first identify them from unusually flat, mirror-like patches in radar surveys of the ice sheet's underside, and confirm some through satellite measurements of the ice surface rising and falling as a lake beneath it fills and drains. Lake Vostok, the largest and by far the most extensively studied, is covered in its own dedicated page on this site, including the 2013 "unknown life" controversy that followed Russia's 2012 drilling breakthrough.

Common Misconceptions

A separate, much less scientifically grounded strand of "Antarctic anomaly" claims circulated widely between 2024 and 2026, recasting ordinary bedrock and gravity data as evidence of buried cities or artificial structures. The pattern is not new: since at least 2016, pyramid-shaped peaks in Antarctica's Ellsworth Range have circulated in social media posts as supposed ancient pyramids. Snopes rated the claim false in 2017, citing glaciologist Eric Rignot's assessment that the feature is simply "a mountain that looks like a pyramid," a nunatak, or rock peak, shaped into a roughly symmetrical horn by glaciers eroding it from multiple sides at once, a well-documented and unremarkable landform in heavily glaciated terrain. A related 2022 hoax claiming the US Marine Corps was investigating "three ancient pyramids" in Antarctica was independently debunked by fact-checking organisations and traced to no genuine military source.

The most recent wave attached itself to real science. When the University of Edinburgh and Dartmouth College published a landmark bedrock map in the journal Science in January 2026, revealing roughly 72,000 previously uncharted hills and extensive canyon systems using a new technique that infers buried terrain from how ice ripples as it flows over it, the underlying research was a genuine advance aimed at improving predictions of future ice loss and sea-level rise. Within days, edited or entirely unrelated images began circulating on TikTok and X captioned as a "secret government base," "remnants of Atlantis," or an "alien landing pad" beneath the ice; some posts used fictional world-building maps sourced from art-sharing sites and presented them as the actual scientific imagery. A separate, unrelated claim in February 2026 that a livestream showed Antarctica's "ice wall" was traced to footage filmed in Patagonia, a different but related pattern of Antarctic misinformation examined on this site's ice wall page.

Glaciologists reject the "lost structure" reading for a consistent set of reasons. Radar and gravity instruments return the shape, density, or reflectivity of what lies beneath the ice, not its material composition or origin, so a symmetrical-looking return is compatible with ordinary directional glacial erosion just as readily as with construction, much as sonar imagery of the Baltic Sea anomaly produced a similarly geometric-looking, and similarly natural, rock formation. No drilling programme, ice-core expedition, or overland traverse has ever recovered artificial material, tooling marks, or archaeological evidence from beneath the Antarctic ice sheet, and no peer-reviewed paper has proposed an artificial origin for any of the features these claims cite. The claims form part of a broader pattern of Antarctica conspiracy narratives that also includes hidden Nazi bases and hollow-earth entrances, sustained less by any specific evidence than by how little independent public access to the continent exists to check a dramatic claim against.

Current Consensus

Several of the features covered here are settled, directly measured facts: the Gamburtsev Mountains' existence and Gondwana-era origin are established through decades of radar, gravity, and magnetic survey data, the Maud Rise polynya's 2016-17 recurrence now has a published physical explanation, and hundreds of subglacial lakes have been catalogued and are the subject of ongoing, publicly documented research. The Wilkes Land gravity anomaly's origin, by contrast, remains genuinely open: geophysicists have not resolved whether it records an ancient impact or a mantle plume, and may not be able to until the ice sheet retreats far enough, or drilling technology advances far enough, to recover a physical sample. What is not supported by any published research is the claim that radar or gravity data have revealed artificial structures, cities, or a hidden civilisation beneath the ice; every specific instance traced by researchers and fact-checkers has resolved to a natural landform, an unremarkable geophysical dataset, or in the more recent cases, an AI-generated or entirely fictional image passed off as scientific imagery.

Why This Mystery Endures

Antarctica's subsurface endures as a magnet for anomaly claims because it is observed almost entirely through instruments rather than eyes: a "mass concentration," a "hole the size of Switzerland," or "72,000 hidden hills" are genuine scientific findings that arrive already phrased in the dramatic language headlines are built from, and need remarkably little embellishment to be repurposed as evidence of something hidden. That gap between a striking dataset and a comparatively mundane physical reality is the same mechanism this site has traced in the Baltic Sea anomaly, where a single sonar image outran the far less dramatic geology it actually depicted, and it compounds with the structural condition explored in why so many conspiracy theories involve Antarctica: a continent with almost no independent civilian population to contradict a viral claim firsthand. This page is part of this site's broader debunked myths coverage.