A walk along the lake
By one estimate, 117 million lakes dot the Earth, covering close to 4 percent of the land area that's not already taken up by glaciers. If you calculate the size of all those lakes — researchers counted only those with a surface area of about a half-acre and up, so that backyard pond may not have made the cut — we're talking about 2 million square miles of Earth that is considered lake water.
And the study didn't even include what many people consider the world's biggest lake, the Caspian Sea (pictured). That would add close to another quarter-million miles to the total. The Caspian Sea is big.
Here's a list of some of the biggest lakes in the world, from the bottom up. A true top 10 is hard to come by since lakes are constantly changing in size. The Aral Sea in Russia, for example, has shrunk precipitously as rivers that feed it have been diverted.