Lake Baikal

Lake Baikal sits in a giant crack in the ground.

Very slowly, the land here is pulling apart. The crack got deeper and deeper over a very long time. Water filled it up and made a lake.

Lake Baikal fills a rift, a place where pieces of the Earth's crust are pulling apart. Mountains surround the lake, and its water fills the long, deep trough between them.

Under the water there is even more. Over millions of years, mud and sand have piled up on the lake floor, a layer more than 7 kilometers thick. The USGS says the solid rock at the bottom of the rift may be 8 to 9 kilometers down. Geologists study Baikal to learn how continents begin to split, the first step toward making a new ocean.

IUCN's assessment describes Baikal as a rift lake at the center of the still tectonically and seismically active Baikal Rift Zone, part of a continental-scale rift system that has existed since the Mesozoic. Citing V. D. Mats, it divides the lake's history into an Archaeo-Baikal stage (about 70 to 30-27 million years ago), a Pre-Baikal stage (about 30-27 to 3.5 million years ago) and the present Lake Baikal stage (the last 3.5 million years).

USGS and Russian seismic surveys found sediments more than 7 km thick, confined in places to a trough 15 to 20 km wide, with the rift floor perhaps 8 to 9 km deep, making it one of the deepest active rifts on Earth. The USGS calls the rift a modern analog for how Atlantic-type continental margins formed, 'the first chapter' of how continents separate into ocean basins. The USGS notes that, unlike other large high-latitude lakes, its sediments were never scoured by continental ice sheets; US and Russian studies of sediment cores traced the past 250,000 years, and drilling from 1993 aimed at about 5 million years.

In winter, Lake Baikal freezes over.

The ice gets very thick and strong. In spring it melts slowly. The south melts first. The north melts last, in early summer.

Every winter, thick ice covers Lake Baikal. NASA explains that ice starts forming in late December, and by mid-January the whole lake is usually frozen. The ice can be strong enough for cars to drive on, and runners even race across it in an ice marathon. Because the lake holds so much summer heat, it rarely freezes early in the fall.

In spring, open water appears in the south in early May, and the last ice in the north does not melt until late June. At Listvyanka, a village on the shore about 70 kilometers from Irkutsk, people have recorded the freezing and melting of the ice every year since 1869.

NASA's Earth Observatory describes the annual cycle: ice formation begins in late December and usually covers the lake by mid-January; in spring, patches of open water appear in the south in early May and move north, with the last ice gone from the northern reaches by late June. The lake's large volume lets it keep summer heat through the autumn, so it rarely freezes early, although in extremely cold conditions it may freeze in December.

The Listvyanka station has kept uninterrupted records since 1869. NASA reports a study by a Swiss researcher finding that thawing moved earlier by about half a day per decade from 1869 to 1999, fastest (about 3 days per decade) between 1869 and 1920; since 1920 break-up there has been fairly constant, but freeze-up comes later, so the ice season is shorter. Satellite altimetry analyzed by Alexei Kouraev's team for 1992 to 2004 showed the central and northern lake behaving differently, and NASA notes the reasons for the changes were still to be sorted out.

Lots of animals live in Lake Baikal.

Many of them live only here, in this one lake! The Baikal seal swims in the cold water. Tiny shrimp-like animals, sponges and special fish live here too.

UNESCO says Lake Baikal's great age and isolation have produced one of the world's richest and most unusual collections of freshwater animals, many of them found nowhere else. Living things like this are called endemic. UNESCO notes that the lake is known as the 'Galápagos of Russia'.

Scientists have counted about 2,640 kinds of invertebrates, animals without backbones such as sponges, snails and tiny shrimp-like amphipods, in the lake, and more than half of them are endemic. The best known is the Baikal seal, which lives only here. Of the 61 kinds of fish recorded, 39 are endemic, including the Baikal omul and two kinds of oilfish that live out in open water. On the lake floor, endemic sponges form underwater forests.

IUCN's 2025 assessment counts about 2,640 invertebrate species (about 56 percent endemic), including sponges, flatworms, snails, amphipods, copepods and caddisflies, plus about 1,000 aquatic plant species (about 15 percent endemic) and 560 algae. Sideleva (2003) recorded 61 fish species, 39 endemic; the cottoid sculpins alone number 33 species and subspecies, 45 percent of the world's freshwater sculpins. Endemic vertebrates include the Baikal seal (Pusa sibirica), the Baikal omul (Coregonus autumnalis migratorius), a Baikal sturgeon and two pelagic oilfish (Comephorus).

UNESCO attributes this fauna to the lake's age and isolation. Around the shore, IUCN reports about 70 mammal species on each of the northern and southern shores and more than 300 bird species, including the Critically Endangered Siberian crane, and notes the Selenga Delta, part of which is a Ramsar wetland. The same assessment warns that the endemic Lubomirskiidae sponges, the coastal zone's main natural biofilters, are dying across the whole lake.

Visitors walk only on the marked paths.

They make campfires only in the special places for fires. Never feed or chase wild animals. Never leave litter. In winter, the ice can crack, so trips onto the ice go with guides who know it well.

Much of Baikal's shore is protected. In Pribaikalsky National Park, visitors need a permit and must stay on set tourist routes. Tents and campfires are allowed only in places made for them, and visitors must not damage trees, scratch writing on rocks or trees, harm animals or destroy nests, or litter. Anyone who sees a forest fire should report it at once.

In winter, the ice can have dangerous cracks: Russia's government newspaper, citing experienced travelers, said there are many before mid-February. It also reported that organized trips with experienced guides include ice-safety measures, and that in February 2026 the official ice crossing to Olkhon Island had still not opened because the ice was unstable.

People are working to protect the lake. A paper mill that polluted the water closed in 2013, and commercial fishing for omul was banned in 2018.

The Zapovednoe Pribaikalye administration's rules for Pribaikalsky National Park allow visits only with a permit naming the group, route and dates; camping and fires only at designated sites; and no vehicles off set routes, damage to trees, graffiti on rocks, trees or buildings, catching animals or destroying nests, dogs running free, or collecting of minerals or plants without permission. Visitors must follow state inspectors, observe forest fire-safety rules and report fires. In the Baikal-Lena reserve, feeding or disturbing wild animals is forbidden. Rossiyskaya Gazeta (25 February 2026), citing experienced travelers, warned of many ice cracks before mid-February and reported the official Olkhon crossing still closed that winter because of unstable ice.

IUCN rates the conservation outlook 'significant concern' (2025): degrading water quality, mass growth of Spirogyra algae over more than 30 percent of the coastal zone (Timoshkin et al., 2016), heavy metals, plastic, rising tourism around Olkhon Island and Listvyanka, coastal fires and water-level regulation. Positive steps include the closure of the Baikalsk Paper and Pulp Mill in 2013, with site remediation underway, and the 2018 ban on commercial omul fishing, after which IUCN says the omul's decline appears to have been halted, though at a lower level than in the past.