Lake Vostok is one of the most unusual lakes on Earth. Buried beneath the East Antarctic Ice Sheet, the subglacial lake has never been directly seen by humans. Scientists discovered it through radar observations in the 1990s and have since used ice-penetrating radar drilling and other techniques to study its size and characteristics.
Despite having a smaller surface area than all five of North America’s Great Lakes Lake Vostok contains an enormous volume of water because of its depth.
A lake hidden beneath kilometres of ice
Lake Vostok stretches for roughly 250 kilometres and is about 50 kilometres wide. Estimates put its surface area at around 12,500 to 15,690 square kilometres, smaller than Lake Ontario, the smallest of the Great Lakes by surface area.
The lake lies beneath approximately 3,700 to 4,100 metres of Antarctic ice. This means that several kilometres of solid ice separate its water from the atmosphere.
The lake was discovered through radar surveys that revealed a large body of liquid water beneath the ice sheet. Its existence has made it an important target for scientists studying extreme environments and the possibility of life in isolated bodies of water.
More water than three Great Lakes
Although Lake Vostok is smaller by surface area, its estimated volume is around 5,400 cubic kilometres, although scientists acknowledge substantial uncertainty in the figure.
That would give Vostok more water than Lake Michigan, Lake Huron and Lake Ontario individually. Lake Michigan contains about 4,920 cubic kilometres of water, Huron about 3,540 cubic kilometres and Ontario about 1,640 cubic kilometres.
Only Lake Superior, with about 12,100 cubic kilometres of water, contains substantially more water than Lake Vostok among the Great Lakes.
The difference is largely explained by depth. Vostok is a relatively compact lake compared with the Great Lakes but extends hundreds of metres downward beneath the ice.
Far deeper than the Great Lakes
Lake Vostok is also much deeper than any of North America’s Great Lakes.
Estimates place its deepest areas at roughly 800 metres, with some measurements suggesting depths exceeding 1,000 metres. Lake Superior, the deepest of the Great Lakes, reaches about 406 metres.
This means Vostok can be roughly twice as deep as Superior and many times deeper than the shallower Great Lakes.
How can the water remain liquid?
One of the most remarkable features of Lake Vostok is that its water remains liquid despite being located beneath an enormous mass of ice in one of the coldest regions on Earth.
The water temperature is estimated to be around minus 3°C. The enormous pressure created by the overlying ice lowers the freezing point, while geothermal heat from beneath the lake provides additional warmth. The thick ice sheet also acts as insulation.
The environment is therefore very different from an ordinary surface lake. Instead of being exposed to sunlight and the atmosphere, Lake Vostok is enclosed beneath kilometres of ice.
An extremely isolated environment
Scientists estimate that Lake Vostok has been isolated beneath the Antarctic ice sheet for millions of years. Some estimates place the isolation period between roughly 15 million and 25 million years.
This makes the lake an exceptional natural laboratory for studying environments that have remained separated from the surface for extraordinarily long periods.
The Great Lakes, by comparison were largely shaped and filled following the retreat of continental ice sheets during the last Ice Age, roughly 14,000 years ago.
Why scientists are interested in Lake Vostok
Lake Vostok is of particular interest to scientists because it provides a possible analogue for environments beyond Earth.
Jupiter’s moon Europa and Saturn’s moon Enceladus are believed to contain subsurface oceans beneath layers of ice. These environments are hidden from direct observation in much the same way that Lake Vostok is concealed beneath Antarctica’s ice.
Studying how water, chemistry and potentially microorganisms behave in Lake Vostok could therefore help scientists understand whether life might survive in isolated, ice-covered environments elsewhere in the solar system.
Drilling into a hidden lake
Russian researchers spent years drilling through the Antarctic ice sheet above Lake Vostok. In February 2012, a drilling operation reached the lake at a depth of about 3,769 metres.
Subsequent work recovered ice believed to have frozen from lake water. The research raised scientific interest but also concerns about contamination because researchers had to penetrate thousands of metres of ice to access the environment.
Scientists therefore face a difficult balance between obtaining samples and preserving an ecosystem that has remained isolated for millions of years.
The numbers are not exact
Measurements of Lake Vostok carry significant uncertainty because scientists cannot simply survey it from the surface.
Radar observations and other remote measurements have produced different estimates for its area, depth and volume. Some estimates put its surface area between roughly 12,500 and 15,690 square kilometres, while volume estimates have a large margin of error.
For this reason, comparisons with the Great Lakes should be viewed as estimates rather than precise measurements.
Lake Vostok vs. the Great Lakes
Lake Vostok is smaller in surface area than every Great Lake but is much deeper. Its estimated volume exceeds that of Lake Michigan, Lake Huron and Lake Ontario, while Lake Superior remains substantially larger by volume.
Its extraordinary combination of depth, isolation and location beneath several kilometres of ice makes it unlike any of the Great Lakes.
Unlike the Great Lakes, Vostok has no accessible shoreline, beaches, ports or surface waves. It is a hidden body of liquid water beneath Antarctica, making it one of the most unusual lakes known to science.
EDITOR: MS. VAISHALI VERMA