Lake Baikal
The world's deepest, oldest, and most voluminous lake
Baikal is a superlative made liquid. The deepest lake on Earth, the oldest, and the single largest reservoir of unfrozen fresh water anywhere, this crescent in southern Siberia holds roughly a fifth of all the liquid fresh water on the planet — more than all five North American Great Lakes combined. Its water is famously clear, frozen solid for months each winter into a sheet of glassy, cracking ice. Locals call it the Sacred Sea, and the title fits a lake that is less a body of water than a continent's deep, cold memory.
Baikal sits in the deepest continental rift on Earth, a crack still slowly widening, and its floor lies 1,642 metres below the surface — with kilometres of sediment beneath that hiding a far older basin some 25 to 30 million years old. Such antiquity and isolation have bred a riot of endemic life: the freshwater Baikal seal, the world's only exclusively freshwater pinniped, glassy translucent fish, and tiny shrimp-like crustaceans that scour the water clean. Oxygen reaches even its greatest depths, an oddity among deep lakes, sustaining life all the way to the bottom.
Designated a UNESCO World Heritage site, Baikal has long drawn scientists, pilgrims, and writers to its shores and the old Trans-Siberian Railway that skirts its southern rim. The Buryat people regard it as holy ground. Yet even this remote giant faces pressure — a now-shuttered paper mill that polluted its waters for decades, algal blooms near settled shores, and the slow warming of its winters, which shortens the ice season that defines life around the lake. It remains, by almost any measure, the most extraordinary lake on Earth.