Today’s Wonder of the Day was inspired by Lily. Lily Wonders, “Why are some lakes bigger than others?” Thanks for WONDERing with us, Lily!

When you think of the most famous lakes in the world, which ones come to mind? Maybe one of the Great Lakes, such as Lake Huron, Lake Ontario, Lake Michigan, Lake Erie, or Lake Superior? Perhaps you think of Great Salt Lake in Utah? Crater Lake?

If you're fascinated by record-breaking lakes, there's another lake that should definitely be on your radar: Lake Baikal. Located in the remote Siberia region of Russia not far from the border with Mongolia, Lake Baikal can boast of at least three superlatives.

First of all, Lake Baikal can claim the title of largest freshwater lake (by volume) in the world. How much water does it hold? Scientists estimate Lake Baikal has a volume of approximately 5,521 cubic miles of water.

That's a lot of water. In fact, it's about 20% of the world's non-frozen fresh water. It's also about the same amount of water contained in all five of the Great Lakes combined.

How can Lake Baikal hold so much water? One of the primary reasons is that it's also the world's deepest lake. Its maximum depth is 5,354 feet (more than a mile!) and its average depth is 2,442 feet.

It's also a very large lake, with a total length of almost 400 miles and an average width of nearly 30 miles. Overall, Lake Baikal has a surface area of 12,248 square miles.

In addition to being the world's largest and deepest lake, Lake Baikal is also the world's oldest lake. Scientists believe it was formed over 25 million years ago when seismic activity fractured Earth's crust, widening what was probably already a large riverbed.

Today, its shores continue to move apart at the rate of about two centimeters each year. Some geophysicists believe Lake Baikal will eventually become an ocean millions and millions of years from now.

More than 300 streams and rivers feed into Lake Baikal. Its only outlet, however, is the Angara River, which carries nearly 16 trillion gallons of water each year into the Yenisei River and, eventually, the Arctic Ocean.

Due to the runoff of melting ice from the surrounding mountains, along with the absence of mineral salts and the presence of debris-eating plankton, Lake Baikal has some of the clearest water in the world. In the spring, it's sometimes possible to see as far as 130 feet below the surface!

Lake Baikal was declared a UNESCO World Heritage Site in 1996 due to its spectacular biodiversity. Of the more than 3,700 species of plants and animals found in and around Lake Baikal, nearly 80% of them are endemic, meaning they can't be found anywhere else in the world. The most famous of these is probably the nerpa, the world's only seal that lives exclusively in freshwater.

Despite freezing over every winter and maximum summer water temperatures of around 50˚ F, Lake Baikal is a popular tourist destination, drawing about a half-million tourists each year. In recent years, however, the lake has been facing new threats.

Climate change and untreated agricultural and industrial sewage have led to increasing problems with Spirogyra algae blooms. These toxic algae harm other species and emit a foul odor when they wash up on shore.

Wonder What's Next?

Tomorrow’s Wonder of the Day features one of the most awesome moves you’ll ever see on the soccer pitch!