With about 20% of Earth's unfrozen freshwater supplies, Lake Baikal is the deepest and oldest freshwater lake worldwide. Its amazing blue waves have depths of up to 5,387 feet and great clarity thanks to unusual microscopic shrimp that filter the water. With an estimated 25–30 million years, the age of the lake has let hundreds of indigenous species evolve, earning it the moniker "Galapagos of Russia." Because the lake is in an active continental rift zone, where tectonic plates are gradually separating, its amazing depth results. The lake freezes remarkably clearly in winter, producing large transparent ice sheets with distinct patterns and structures. Because the lake's water is so pure that visibility reaches 40 meters below the surface, researchers may closely examine its special ecosystem. While thermal vents on the lake floor sustain unique deep-water habitats that have evolved in isolation for millions of years, the surrounding mountains and geological formations help to minimise silt reaching the lake, therefore preserving its clarity.