Hello, and welcome to what will become another series of headers I only manage to return to sporadically: counting down the world’s largest lakes.

We begin, already, with controversy, as not everyone considers the Caspian Sea to be a lake – it’s right there in the name, after all, it’s a sea, right? Well, while the Caspian is somewhat salty, it is not directly connected to any of the world’s oceans and is surrounded entirely by land, so in my books that makes it a lake.

The Caspian is by far the world’s largest lake, with a surface area of 389,000 km² (150,194 sq mi) and an average depth of 211 metres (690 ft), reaching over 1,000 metres (3300 ft) at its deepest point. The lake is an endorheic basin, meaning that water flows in from rivers like the Volga and Ural, but does not leave except via evaporation. This is what gives the water in the Caspian it’s brackish quality, similarly to the Great Salt Lake or the Dead Sea, though it is far less saline than either of those, and is only about a third as saline as the ocean itself.

The Caspian has a long human history, and is bordered by five countries: Kazakhstan, Russia, Azerbaijan, Turkmenistan, and Iran, and was named after the ancient Casperi people. Unfortunately, that history has not always been positive, as the Capsian is now facing a number of environmental challenges, including heavy pollution in the Volga River, the sea’s main source, and aridification in the Caspian’s shallower northern sections, like its neighbour the Aral Sea. Currently the Tehran Convention provides an avenue for the five Caspian countries to work together to reduce environmental impacts on the lake.

I hope you’ve enjoyed this brief look at the Caspian Sea. Have a great day, everyone!