Siberia's Lake Baikal Is the World's Oldest and Weirdest

Lake Baikal is located in southern Russia, near the border of Mongolia. Its depth of world's deepest lake. The second-deepest lake, Lake Tanganyika in east Africa, is 4,710 feet (1,435.6 meters) deep by comparison. Crater Lake, the deepest lake in the U.S., is 1,900 feet (579 meters) deep.

Lake Baikal's 12,200-square-mile (31,597-square-kilometer) size also makes it Earth's largest. That size, by the way, makes it comparable in volume to the entire Amazon basin. For scale, it reportedly takes about 330 years for one water molecule to flow from inlet to inlet.

So how did Lake Baikal get so massive? About 25 million years ago, Lake Baikal formed through fractures and shifting within Earth's crust. It wasn't Lake Baikal as we now know it, though. Experts believe it was a series of lakes, similar to the Great Lakes in the U.S. While scientists aren't positive how Lake Baikal went from many lakes to the behemoth it is today, they do have theories. It could've been sinking earth, erosion, earthquakes, increased water from melting glaciers — although it's likely a mix of these factors and more.

Now, that unifying change took place in the Pliocene Epoch (about 5.3 to 2.5 million years ago), but this lake is hardly finished growing. It's expanding at a rate of 0.7 inches (2 centimeters) every year — the same speed at which Africa and South America are drifting apart. At this speed, some scientists believe Lake Baikal is actually an ocean in the making.

Of Lake Baikal's 27 islands, the largest is Olkhon, at 280 square miles (725 square kilometers). Olkhon has its own lake, mountains and a population of 1,500 residents. Locals connected to power via an underwater cable in 2005, and were connected to the internet shortly after.

Some call Lake Baikal the "Galapagos of Russia" not only because it has an impressive array of nearly 4,000 species, but also because 80 percent of those animals are found nowhere else. One reason for Lake Baikal's unique biodiversity is its array of hydrothermal vents. These hydrothermal vents are commonly found in oceans, but Lake Baikal is the only freshwater lake known to have them.

So how do these hydrothermal vents work? Cold lake water enters cracks in Earth's crust through the vents. When the water reaches magma, it heats up, then returns, resurfacing with minerals and heat.

These rich minerals are the reason for some of Lake Baikals' most unusual species, including the Baikal omul fish, the Baikal oil fish, and the star of the show: the Nerpa seal species. Like Lake Baikal, the Nerpa seal is itself a natural phenomenon. It's the only exclusively freshwater seal species in the world, and its evolution — given other seals are found in the ocean — is mysterious. Some scientists believe it arrived via a prehistoric river from the Arctic.

Beyond seals and fish, other common animals found in the forests and mountains surrounding Lake Baikal include bears, elk, reindeer, lynx, wild boar and of course, the lake's frequently reported "Water Dragon Master."

Lake Baikal is more than a natural wonder or wildlife haven. For about 100,000 permanent residents, it's home. The population spans multiple ethnic groups: Buryats (Siberia's largest Indigenous people), Evenks and Russians. Their main occupations are forestry, agriculture, fisheries, hunting and tourism. As adventure and off-the-grid tourism grows, the latter is particularly on the rise.

The Baikal area sees about 30,000 visitors per year, according to Euro News. Karen Zhao, a local expert and Intrepid Travel product manager for North & Central Asia, says there are a handful of ways to enjoy this still-hidden gem. Intrepid's tours, such as Beijing to Moscow and the Trans-Mongolian Experience, both include a stop.

"The best way to experience Lake Baikal is to stay with a local family or at a local guesthouse near the lake. Here, you can experience the Baikal hospitality firsthand," she says via email. "During the day, you can take a boat tour on the lake, go on a hike on the Baikal trail, visit the larger islands, and also stop at some ethnographic museums and villages."

The days conclude with a visit to the host's banya, a Russian-style sauna, although be prepared: These hot-sauna visits end with a "refreshing" dip in the chilly lake. That is, until it freezes over. But winter brings its own type of adventure, too.

"Winter is also one of the best times to visit Baikal, from late January to early March, when the lake is fully frozen," Zhao says. "Baikal is famous for its purity of water and on a good day, you are able to see 40 meters [131 feet] deep into the lake. So when the lake is frozen, you'll be able to see the beautiful transparent blue ice that echoes the color of the sky or see a huge air bubble frozen inside the lake, too."