Lake Baikal

Make sure you have a drysuit for this epic underwater adventure.

Olga Kamenskaya

Situated in southeast Siberia, Lake Baikal spans an area the size of Belgium. It is the world's oldest, deepest and largest lake, and contains 20 percent of all fresh, running water on the planet. It's so vast that Siberian people call it a sea. When its surface freezes, the ice sheet is so clear that it is possible to see right through it. The transparency is a result of its exceptionally clean water — in fact, it can be considered distilled. Minerals like calcium or sodium salts, which would other- wise make the ice opaque, are found only at very low levels here. The visibility makes Baikal a fantastic dive site, but few have the courage to withstand the near-freezing temperatures. Many people fear Baikal’s depths — in the breathtaking abyss, one feels like a tiny helpless bug in an immense world. But divers who take the plunge discover a magical underwater park.