How Deep Is Lake Baikal Really? Nearly Five Eiffel Towers

How deep is Lake Baikal? Most people guess a few hundred meters, since it's just a lake. Spoiler: Lake Baikal in Siberia is about 1,640 m (5,380 ft) deep. That's nearly five Eiffel Towers stacked on top of each other. Its floor even sits more than 1,000 m below sea level, although the shore is high above the ocean. On top of that, it holds about one in every five liters of the liquid fresh water on Earth's surface. We'll show you the numbers, the comparison with the Great Lakes, and why this lake is so special.

How deep is Lake Baikal?

Lake Baikal is about 1,640 m deep at its deepest point. Sources give slightly different values between 1,620 and 1,642 m, depending on the measurement. The average depth is around 744 m (2,440 ft). That makes it the deepest lake on Earth.

For context: the Eiffel Tower is roughly 330 m tall. Nearly five of them fit on top of each other inside Lake Baikal. Even the Burj Khalifa, at 828 m, would disappear, with about 800 m of water left above it. Most people guess a few hundred meters for a lake. That's the classic mistake: we think of swimming lakes, not of an inland sea.

Why is the bottom of Lake Baikal below sea level?

The surface of Lake Baikal sits about 455 m (1,494 ft) above sea level. But the lake is so deep that its floor lies roughly 1,200 m below sea level. So you stand on the shore far above the ocean and look at water whose bottom is lower than the sea.

The reason is what lies underneath. The lake sits in a rift valley, the Baikal Rift Zone, where the Earth's crust is slowly pulling apart. The valley sinks and water fills it. The ground there shakes a lot: up to 2,000 small tremors are detected each year.

How much water is in Lake Baikal?

Lake Baikal holds roughly 23,000 cubic kilometers (5,500 cubic miles) of water. Sources give 23,013 or 23,615, depending on the study. The five Great Lakes between the US and Canada add up to about 22,700 cubic kilometers. So Baikal alone holds at least as much water as all five together.

Yet its surface is much smaller. Lake Baikal covers about 31,700 km² (12,250 sq mi), while the Great Lakes together cover around 244,000 km² (94,000 sq mi). The Great Lakes are huge in area. Lake Baikal is huge in depth.

How big is Lake Baikal on the surface?

The lake is about 636 km (395 mi) long and at most 79 km (49 mi) wide. Its area is slightly larger than Belgium. On a map it looks long and narrow, which hides how deep it is. Estimates say up to 330 rivers and streams flow in. But there is only one outlet: the Angara River.

How old is Lake Baikal and what lives there?

Lake Baikal is about 25 million years old. Sources range from 20 to 30 million years. That makes it the oldest lake on Earth. It has been a UNESCO World Heritage Site since 1996.

The lake is home to the nerpa, the Baikal seal. It is the world's only seal that lives exclusively in fresh water, and it exists nowhere else. Scientists suspect its ancestors swam down a prehistoric river from the Arctic.

In winter the lake freezes over from about January to May. The ice is 0.5 to 1.4 m thick on average (1.6 to 4.6 ft) and over 2 m (6.6 ft) in some places.

Want to test how well you can guess sizes and depths? Try our geography estimation questions. Free, and they run right in your browser.

Lake Baikal questions and answers

The takeaway in one sentence

Lake Baikal isn't a big lake, it's an inland sea built downward: about 1,640 m deep, about 25 million years old and packed with water. For more records, read How Deep Is the Deepest Hole in the World? and How Long Is the Longest River in the World Really? And if you want to test your feel for numbers, play a round on Quiztimate.