The Lakes & Rivers Of Antarctica: Lake Vostok, Onyx River & More

Water in its frozen forms—snow and, especially, ice—dominates Antarctica. This is the White Continent after all, with all but a tiny fraction of the land surface covered by ice. But what about in liquid form?

The only liquid water we tend to think of in connection to Antarctica is the seawater of the Southern Ocean, which itself comes extensively roofed over during the austral winter by sea ice.

So there’s frozen water and seawater, sure, but does Antarctica have rivers? Are there lakes in Antarctica? You may be surprised to learn that the answer on both counts is definitely—both above (surficial) and below (subglacial) Antarctica’s ice sheets!

Antarctic Lakes

Surficial Antarctic Lakes

Antarctica includes some surface lakes, which exist in ice-free “oases” such as the McMurdo Dry Valleys—host to more than a dozen good-sized lakes, from Bonney and Buddha to Vida and Vanda, as well as many ponds—and the Bunger Hills (where Algae Lake ranks as the largest of numerous lakes and pools). Many of these are saline, including the most notable of Antarctica’s surficial lakes found below:

Lake Vanda

Among the numerous hypersaline lakes and ponds in the McMurdo Dry Valleys of the Transantarctic Mountains—the most extensive ice-free oases on the White Continent—Lake Vanda is the largest and, at some 226 feet (69 m) deep, the deepest. It’s situated in the lowest portion of Wright Valley, set between the Olympus and Asgard ranges. Notably, the Onyx River, the longest river in Antarctica, flows into Lake Vanda during the summer, feeding it glacial and snowfield meltwater.

Mostly lidded with ice year-round, Lake Vanda is surprisingly toasty down below: The hypersalinity at depth (about 35 percent salt content) creates a temperature inversion, allowing its bottom waters to approach 80 °F (27 °C). Indeed, it’s the warmest-known of all Antarctic lakes.

Don Juan Pond

Lake Vanda ranks among the most saline bodies of water on Earth, but the nearby Don Juan Pond, another landmark of Wright Valley, beats it out: With a salinity of about 44 percent, it’s sometimes called the saltiest lake in the world. (You can read much more about Don Juan Pond here.)

Lake Bonney

Lake Bonney is the second-largest of the McMurdo Dry Valleys’ iced-over saline lakes, after Vanda. Located in Taylor Valley, it edges up against the Taylor Glacier at its western shore. Here, famously, the gory crimson stain of Blood Falls (more about that remarkable feature here) soaks the ice and glacial moraine overlooking the lakeshore.

Subglacial Antarctic Lakes

The largest share of major Antarctic lakes, however, lie buried several kilometers beneath the mighty ice sheets that dominate the White Continent. More than 475 such subglacial lakes in Antarctica, situated where the base of the ice sheet meets bedrock, have been identified by scientists, accounting for the vast majority of those documented on the planet. (Others are known from beneath the Greenland Ice Sheet and some ice caps in Iceland and the Canadian Arctic Archipelago, as well as certain alpine glaciers.) Some lie near the center of the ice sheet associated with ice divides, others under fast-flowing ice streams, and others along the ice-sheet margins.

These lakes under Antarctica (if you will) are among the most head-spinningly remote bodies of water on the planet, and their extreme environment—challenging to research as it is—tantalize scientists on a number of counts. Their water chemistry and sediments offer clues into the history of the ice sheets that overlie them,  for one thing. And, furthermore, Antarctic subglacial lakes’ surprising biological activity may hold insights into potential life elsewhere in the Solar System.

Some cutting-edge research into these under-ice freshwater lakes has been going down on the White Continent in recent decades, via such initiatives as SCAR’s Subglacial Antarctic Lake Environments (SALE) Program and the Subglacial Antarctic Lake Scientific Access (SALSA) Project funded by the U.S. National Science Foundation.

Subglacial lakes in Antarctica are maintained, it’s thought, by the sheer pressure of the overlying ice—which keeps them liquid even at subfreezing temperatures—as well as the movement and deformation of the ice sheet and, in at least some cases, contribution from geothermal heat producing meltwater, but they may also be connected to deeper-yet subglacial aquifers (some of which have been identified as briny reservoirs of fossil seawater).

The following are just a handful of the numerous subglacial lakes documented on the White Continent:

Lake Vostok

What is the largest lake in Antarctica? That’d be Lake Vostok, also the biggest subglacial lake on the planet, as well as one of the largest, deepest, and most voluminous lakes of any kind. Situated on the Antarctic Polar Plateau near Russia’s Vostok Station, it’s thought to have originally existed as a surface lake, but was swamped by the growth of the East Antarctic Ice Sheet perhaps 15 or even 25 million years ago. It now lies beneath some 2.5 miles (4 km) of ice.

Despite the apparent great antiquity of the lake, the lakewater itself is thought to be of younger vintage, with a cycle of “outflow” by freezing and transport by the ice sheet and inflow via ice-sheet meltwater, some of it perhaps from “upstream” in the subglacial hydrologic system.

About 150 miles (240 km) long and 31 miles (50 km) wide, Lake Vostok—first suspected by Russian researchers back in the 1960s, but not confirmed until 1993—is comparable in area to Lake Ontario (part of the North American Great Lakes). An underwater ridge separates the deeper, southern part of the lake—which may be at least close to a mile deep—from the shallower section. There’s some speculation that Lake Vostok, situated in a tectonic collision zone, may occupy a small rift valley, and that the ridge dividing its shallower and deeper parts may represent a hydrothermal-vent system similar to what’s seen in places on the ocean floor.

Sampling from Lake Vostok has revealed a diverse microbial community—bacteria, fungi, archaea—in the so-called accretion ice that connects its surface to the mobile ice sheet above. There’s a mix of both freshwater- and marine-affiliated microbes, suggesting this subglacial lake once connected to the ocean, and the extremophiles here include both heat- and cold-adapted species.

Lake Vostok’s genuine faunal inventory is interesting enough, but, perhaps not surprisingly given the size and almost alien location of this waterbody, it also can lay claim to its very own cryptid—i.e., a creature existing beyond the bounds of scientific acceptance (and mostly in the domain of science fiction). You can learn more about Lake Vostok’s fictional Organism 46b—an alleged giant, venomous, shapeshifting octopus-like beast—here.

Mercer Lake

Situated under the West Antarctic Ice Sheet’s Mercer and Whillans ice streams a few hundred miles away from the South Pole, Mercer Lake is another of the mysterious Antarctic subglacial lakes that’s lately yielded some fascinating information about these hidden-away ecosystems—and the broader geologic history of Antarctica—thanks to the intrepid efforts of polar scientists.

A roughly seven-foot-long sediment core was retrieved from Mercer Lake during the 2018-2019 SALSA expedition, which revealed that, only a few thousand years ago, the edge of the West Antarctic Ice Sheet lay 155 miles (250 kilometers) or more inland from where it does today, hinting at how—and how quickly—ice sheets respond to climatic shifts.

That research also shed light on the diverse microbial community within Mercer Subglacial Lake: Bacteria, archaea, and other microbes here obtain energy partly from carbon introduced some 6,000 years ago from a marine source when the lake was linked to the Southern Ocean as well as carbon from upstream sources in the subglacial drainage network, and also, via the process known as chemosynthesis, from minerals sourced from bedrock pulverized by the ice sheet.

The SALSA fieldwork at Mercer Lake, by the way, is profiled in the fine feature-length documentary, The Lake at the Bottom of the World.

Lake Ellsworth

Discovered in 1996, subglacial Lake Ellsworth occupies a deep-set trough about 1.86 miles (3 kilometers) under the West Antarctic Ice Sheet. Named for the discoverer of the relatively nearby Ellsworth Mountains, the polar explorer Lincoln Ellsworth,  this roughly 12-square-mile (29-square-km) subglacial lake is about 490 feet (150 meters) deep.

In 2012, an ambitious attempt was made to drill down to Lake Ellsworth and analyze water and sediment for signs of life. The project team was, however, unable to do so due to unforeseen setbacks trying to connect two boreholes, essential for pressure regulation upon penetrating the lake. Though the mission failed to achieve its main objective, it did yield valuable information regarding experimental design and potential routes of contamination—a major cause for concern when trying to study the long-sealed-away waterbodies of subglacial Antarctic lakes.

Antarctic Lava Lakes

It’s worth noting that liquid freshwater and saline waterbodies aren’t the only “lakes” Antarctica plays host to. At least two lava lakes are known from the Antarctic: one on Mount Erebus (the southernmost active volcano known on Earth), another—only discovered in 2019—on Mount Michael, a stratovolcano on Saunders Island in the South Sandwich Islands. Only a handful of these volcanic features have been identified on the planet; others, for example, are found on the Kilauea (Hawaii) and Erta Ale (Ethiopia) shield volcanoes.

Antarctic Rivers

Surficial Antarctic Rivers

Despite a 2023 paper in Nature Communications documenting a vast prehistoric river network predating the East Antarctic Ice Sheet, still discernible in the buried landscape underneath it, today Antarctica has no rivers in the true sense of the word, but does have nine semi-permanent glacial meltwater streams which flow seasonally in Antarctica during the warmer austral summer. However, two do have “river” formally in their name:

Alph River

The Alph River along the Scott Coast of Victoria Land drains the Koettlitz Glacier in the austral summer, and flows through a series of waterbodies as it does so: Pyramid Ponds, Trough Lake, Walcott Lake, Howchin Lake, and Alph Lake. The river was named by Griffith Taylor during the British Antarctic Expedition (1911-13) from a poem by Samuel Taylor Coleridge: “Where Alph the sacred river ran, Through caverns measureless to man, Down to a sunless sea.”

Onyx River

The longest river of Antarctica is the Onyx River in Wright Valley. It rises at Lake Brownworth, which lies at the base of the Wright Lower Glacier, and, in summer, flows westward some 17 miles (28 kilometers) to Lake Vanda. Though its source at Lake Brownworth is not all that far from the Ross Sea to the east, the Wright Lower Glacier blocks the seaward part of Wright Valley, hence the Onyx’s westerly, inland course. And because Lake Vanda has no outflow, the Onyx drainage is an example of a closed basin.

Subglacial Antarctic Rivers

Evidence suggests that many of Antarctica’s aforementioned subglacial lakes—some of which have been detected undergoing filling and draining cycles—are connected via subglacial rivers and channels, forming subglacial meltwater drainage networks that may be somewhat comparable to those we find on Earth’s surface.

Like their subglacial lake counterparts, these subglacial rivers are hotbeds of research into both ice-sheet dynamics and life surviving in extreme environments. It is thought these subglacial waterways may influence the movement of the overlying ice sheet and the delivery of meltwater to the Southern Ocean, with some subglacial flows extending beyond the Antarctic ice sheets into cavities under the ice shelves that form the floating, coastal extension of the ice sheets.

In 2021, scientists drilled more than 1,600 feet down into the Larsen Ice Shelf to confirm the presence of a subsurface river they’d suspected based on a groove on top of the shelf. What they hadn’t expected was that this sub-ice channel would be teeming with amphipods: another example of Antarctic life persisting in what seem like the most improbable places.

[Photo credit: The Onyx River by Melissa Li, NSF, CC BY-NC-ND 4.0.]