The Caspian Sea is huge enough to feel like an ocean. At about 371,000 square kilometres, it’s bigger than Japan and easily the largest body of water on Earth that isn’t connected to the ocean. That technically makes it a lake - the biggest in the world.
It became “trapped” inland millions of years ago, when shifting continents cut it off from the open sea. Even now its water is mildly salty, roughly a third as salty as the ocean. The Caspian sits below sea level, which is part of why its borders shift so much.
Five countries border the Caspian: Russia, Iran, Kazakhstan, Turkmenistan, and Azerbaijan. It’s also home to the beluga sturgeon, a fish that can live over 100 years and is the source of most of the world’s most expensive caviar.
