Someone Put the 25 Largest Lakes on Earth in One Map. So What, Exactly, is a Lake?

A couple of days ago the picture above caught our attention on Twitter and we retweeted it. The folks at a website called the Visual Capitalist had used a nifty online tool called “Slap It On a Map!” to cram the twenty five largest lakes on Earth onto the U.S. and Canada’s square chunk of real estate surrounding the Great Lakes.

“Who let the Caspian Sea in here?” we jokingly asked. We got this reply.

Now, full disclosure, Ben Kraemer is an alumni of the Center for Limnology and he was (we think) not truly insinuating that we were stupid. Regardless, we set out to educate ourselves. “A body of water surrounded by land,” easy, right? Well, no.

What you see above is a nice Google Earth image of the Caspian Sea and the Black Sea. The Caspian Sea is, far and away, the largest lake in the world. The Black Sea doesn’t even rank. Confused yet?

Thankfully, people kept commenting on our Twitter post!

Lisa Borre is a senior research scientist at the Cary Institute of Ecosystem Studies and, if that’s not enough to bestow authority on her ability to tell a lake from a sea, she also literally wrote the book (okay, a book on sailing) the Black Sea. Basically what she’s saying is that, since the Black Sea gets a sizable amount of its inflow is from an oceanic source (the Mediterranean Sea) it doesn’t get to claim a lake title.

So does that mean salt water versus freshwater has anything to do with a lake? Nope. The Great Salt Lake is, obviously, a lake. The key is that it’s not connected to the ocean.

However, this all set us to thinking. The specifics keeping the Black Sea out of this discussion aren’t part of the standard dictionary definition of a lake:

If you take the dictionary at face value then the “Is it a lake?” question can take you to really weird places. Take a closer look at this map of the Mediterranean and Tyrrhenian Seas. They’re really just one body of water surrounded by land, right? You could count the straight of Gibraltar as preventing full land enclosure but, really, from a satellite this looks like a lake.

Not a lake.

And then, if you really want to get crazy, you could follow this train of thought to its logical destination – aren’t the world’s ocean’s just one big lake? We’re not trying to start any fights or destroy any limnological worldviews, but we are going to just leave this final image right here: