Lake Baikal Ice Hummocks: How Turquoise Ridges Form and Where to See Them

Every March, Lake Baikal's frozen surface breaks into fields of turquoise slabs, some standing upright like broken glass, others piled into ridges taller than a person. Russians call these pressure ridges torosy, ice hummocks, and on the world's oldest and deepest lake they are one of the great winter sights of Siberia.

Turquoise ice hummocks on frozen Lake Baikal – photograph by Alexey Trofimov — Photo: Alexey Trofimov.

Lake Baikal, the oldest and deepest lake on Earth

Baikal lies in south-eastern Siberia, between the Irkutsk region and the Republic of Buryatia. UNESCO, which lists it as a World Heritage Site, describes it as about 25 million years old and roughly 1,700 metres deep, making it both the oldest and the deepest lake in the world. It holds about 20 per cent of the planet's unfrozen fresh water.

The lake is about 635 km long and averages around 50 km wide, with a surface of some 3.15 million hectares. Its water is famously clear, and hundreds of its plant and animal species live nowhere else, including the Baikal seal, or nerpa, one of the few freshwater seals in the world.

Ice hummocks on Lake Baikal – photograph by Valery Chernodedov — Photo: Valery Chernodedov.

Second view of Baikal hummock ice – photograph by Valery Chernodedov — Photo: Valery Chernodedov.

How Baikal freezes and how ice hummocks form

Because the lake stores so much summer heat, it freezes late. Shallow bays ice over in November, but the open lake usually closes only in January. Once it has formed, the ice thickens by several centimetres a day and reaches between about 70 cm and 2 metres, thick enough for cars and trucks to cross on official ice roads.

The ice never stops moving. Severe frost makes it contract and split, while wind, sunshine and temperature swings make the plates expand and push against each other. Where two fields collide, the edges break and ride up into piles of blocks, from a few centimetres to a metre or more high. These are the hummocks. Long "main cracks" also open in roughly the same places each winter, sometimes 10 to 30 km long, with booming sounds that carry across the lake.

Clear, snow-free ice is what gives the hummocks their colour. Light passing through thick, bubble-poor ice loses its red wavelengths first, so the slabs glow blue and turquoise, especially at low sun and in the side-lit edges of broken blocks.

Broken blue ice slabs on Lake Baikal – photograph by Daniel Korzhonov — Photo: Daniel Korzhonov.

Baikal ice hummocks in winter light – photograph by Andrey Narchuk — Photo: Andrey Narchuk.

Frozen Baikal surface with ice ridges – photograph by Alexey Kharitonov — Photo: Alexey Kharitonov.

Where to see Baikal ice hummocks

The ice season runs roughly from mid-January to early May, and the best time to visit is February and March, when the ice is thickest and the ice crossings are open. The hummocks are at their most dramatic in March. Most trips start in Irkutsk, which has an international airport and a station on the Trans-Siberian Railway.

Listvyanka, about 70 km from Irkutsk, is the easiest base. You can walk out among the hummocks and see the source of the Angara River, which stays unfrozen all winter.
Bolshoe Goloustnoe, about two hours by bus from Irkutsk, is known for frozen methane bubbles trapped in dark ice. Hovercraft run from there to Peschanaya Bay, where the ice is blue and heavily cracked.
Olkhon Island, the largest island on the lake, is about six hours' drive from Irkutsk via the ice crossing. Its main village is Khuzhir, close to Cape Burkhan, and the ice grottoes and Cape Khoboy are favourite photo spots.
Maloye More, the "Little Sea" between Olkhon and the mainland, is shallow and freezes early, often producing smooth, transparent ice you can see through to the bottom.

Go with a local guide or tour operator: the ice can thin near river mouths and warm-water vents along the shore, and guides know where the safe routes are each season.