Yes, Lake Baikal freezes every winter despite being the deepest lake on Earth. The entire surface, stretching over 31,000 square kilometers, is typically locked under ice from mid-January through late April or May. The ice grows thick enough to support vehicles and creates some of the most visually striking frozen landscapes on the planet.
When the Ice Forms and Breaks Up
Freezing begins in late December as winter air temperatures around the lake average about −21 °C (−6 °F). By mid-January, the entire surface is usually covered. The ice then holds for roughly four months before patches of open water start appearing in the southern part of the lake in early May. From there, the thaw moves progressively northward, and the last remnants of ice in the northern reaches don’t typically disappear until late June.
The lake’s sheer volume of water explains why it takes so long to freeze compared to smaller Siberian lakes. Baikal holds about 20% of the world’s unfrozen surface freshwater, and all that thermal mass resists cooling well into December even as air temperatures plummet.
How Thick the Ice Gets
Ice thickness varies by location. In the northern part of the lake, where winters are coldest and longest, the ice reaches about 1 meter (roughly 3.3 feet). In the south, it’s thinner, averaging around 80 centimeters (about 2.6 feet). Both figures are well above the 30.5 centimeters generally considered safe for cars and pickup trucks on frozen lakes, which is why locals and visitors have long used the ice as a winter road.
Ice Hummocks and Trapped Methane Bubbles
Baikal’s ice is famous for more than just its thickness. In March, when Siberian winds tear across the surface, temperature swings and pressure differences cause cracks to form. Great transparent slabs of ice tilt upward and pile into formations called hummocks, some towering several meters high. Because Baikal’s water is exceptionally clear, these slabs can look like enormous shards of turquoise glass.
Another signature feature is the methane bubbles frozen into the ice. Microbes in the lake’s sediment break down ancient organic carbon, releasing methane gas that rises toward the surface. During summer, these bubbles simply pop at the water’s surface. But as the lake refreezes in fall, the ice grows around the rising gas, trapping it in place. If the bubbles rise slowly, the ice encases them one by one, creating stacked columns of white discs suspended in the clear ice. Faster-rising gas produces larger pockets and pillows of trapped air. The result is a frozen surface studded with patterns visible from above, a phenomenon that draws photographers and tourists from around the world.
Why the Ice Matters for Wildlife
The Baikal seal, or nerpa, is the only exclusively freshwater seal species on Earth, and its survival is tightly linked to the lake’s ice. Females give birth in snow-covered burrows built on the frozen surface, and the ice provides critical protection from predators during the weeks when pups are most vulnerable. As a landlocked, ice-breeding species, the nerpa is considered especially sensitive to any changes in how long the ice lasts each year.
A Shrinking Ice Season
The ice season on Lake Baikal has been getting shorter. Over the past 137 years, the ice-free period has lengthened by about 16 days, driven mainly by the ice forming later in the year rather than melting earlier. Historical records bear this out in the other direction, too: in the 1870s, the spring thaw typically began around May 10, while today it often starts in late April.
That shift of roughly two weeks may sound modest, but it has cascading effects. A shorter ice season means less time for the nerpa to breed safely on the surface, altered conditions for the lake’s unique cold-water ecosystem, and a narrower window for the winter ice roads that connect communities along Baikal’s remote shoreline. In warmer winters elsewhere, studies have documented delays of nearly three weeks in the opening of ice roads, along with a 25% loss of the usable winter road season. Baikal faces a similar trajectory if warming trends continue.