Why the Caspian Sea is actually a lake

Transcript

Why is the Caspian Sea actually not a sea, but a lake? And not just any lake, but the largest lake on Earth by surface area. It stretches for about 750 miles, and five countries share its shores. Powerful storms here bring waves as tall as a three-story building, and in places, it's over 3,000 feet deep, which is enough to cover the world's tallest building. And here's what makes it even more confusing. The water here is salty. It seems to have everything a sea should have, except one thing, a natural connection to the ocean. If you look at the black sea, it might seem cut off, too. But through the Vosporus, and a series of seas and straits, it reaches the Mediterranean, then passes through the Strait of Gibraltar into the Atlantic Ocean. The Caspian, however, is completely landlocked, which is why it's geographically classified as a lake. But then why is the water here salty? You see, the Caspian was once part of a much larger body of water called the Paratethis. Over millions of years, the land rose, water levels changed, and this huge body of water split into separate basins. Some of the Caspian salt comes from that ancient sea, while rivers continue to bring in more. And to ancient people, this huge body of salty water really seemed like a sea. The name stuck, which is why we still call it a sea today. Even though geographically, it's a giant lake.

Transcribed automatically from the video, so small errors are possible.