CryoSat-2 discovers 85 hidden lakes beneath Antarctica
Eighty-five previously unknown subglacial lakes were detected beneath Antarctica between 2010 and 2020, expanding the known active network by nearly 60% and reshaping our understanding of the continent’s hidden water systems, a study published in Nature Communications reports.
Scientists discover 85 hidden lakes beneath Antarctica using satellite radar. Credit: Wilson et al., Nature Communications
Scientists have long known that liquid water lies beneath Antarctica’s thick ice, stored in hundreds of subglacial lakes sealed off from the surface.
Until now, researchers had confirmed 146 active lakes, those whose surface elevation signals cycles of drainage and refilling. The new study, led by scientists using the European Space Agency’s (ESA) CryoSat-2 satellite, adds 85 active lakes to the list, raising the total to 231. Across the continent, the entire lake tally now reaches 766 when inactive features are included.
The discovery represents a 58% increase in known active lakes, a significant revision to our picture of Antarctica’s hidden water systems.
The research team analyzed a decade of CryoSat-2 radar altimetry data collected between 2010 and 2020. Unlike earlier laser altimetry missions such as NASA’s ICESat, CryoSat-2 operates with radar capable of penetrating cloud cover and darkness, offering continuous monitoring of ice-sheet elevation.
A key advance in this study was the use of “swath processing” of CryoSat-2 data. This method reconstructs detailed surface elevation patterns rather than relying solely on single-track measurements. It allows scientists to detect subtle surface rises and falls of only a few meters (feet), the signature of subglacial lakes filling and draining far below.
By tracking surface deformations across Antarctica, the researchers mapped the position and the changing boundaries of lakes, something not possible in earlier surveys.
The majority of the newly discovered lakes, 73 of 85, lie beneath East Antarctica, the continent’s largest and thickest ice sheet while the rest are distributed beneath West Antarctica and along major ice streams.
About 81% of the active lakes were detected beneath fast-moving ice streams, where ice speeds exceed 50 m per year (164 feet per year). This reinforces the link between subglacial water flow and ice-sheet motion.
Six lakes were found within 8 km (5 miles) of the grounding line, the point where the ice sheet detaches from the bedrock and begins to float as an ice shelf. Lakes this close to the ocean interface suggest a potential hydrological link between the continent’s hidden water systems and its coastal ice.
The study recorded 37 complete drainage events and 34 complete filling events. Draining episodes typically lasted a median of 2.2 years, while refilling took around 3.5 years. This is visible at the surface as the ice sheet slowly sags or rises, depending on whether the lake below is emptying or filling.
Some lakes follow smooth filling or draining cycles, others pause in “stepped” patterns, and some even show changes in active area of up to 50% between episodes, suggesting diverse hydrological conditions beneath different regions of the ice sheet.
One of the most striking findings is evidence of hydrological networks beneath the ice. Researchers identified at least five systems where the drainage of an upstream lake coincided with the filling of a downstream lake.
The links confirm that Antarctica’s subglacial lakes do not always act in isolation. Instead, they can transfer water across tens of kilometers through hidden channels, redistributing pressure and affecting ice-sheet behavior on regional scales.
Such networks were hinted at in earlier studies, but the expanded satellite record now provides the clearest evidence yet of continent-wide connectivity in subglacial hydrology.
Subglacial lakes are among the most inaccessible environments on Earth, sealed beneath kilometers of ice for potentially millions of years. Some may host unique microbial ecosystems, making them analogues for icy worlds such as Europa or Enceladus.
References:
1 Detection of 85 new active subglacial lakes in Antarctica from a decade of CryoSat-2 data – Wilson et al. – Nature Communications – September 19, 2025 – DOI: https://doi.org/10.1038/s41467-025-63773-9 – OPEN ACCESS
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