Peak water - here's a thought-provoking illustration...

In this illustration, the blue ball represents the volume of all the water on earth, relative to the size of the earth. The tiny speck to the right of the blue ball represents Earth's fresh water.
CREDIT: David Gallo/WHOI

If Earth was the size of a basketball, all of its water would fit into a ping pong ball.

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Oceans create a water layer spanning 15,000 miles (24,000 kilometers) across the planet at an average depth of more than 2 miles (3.2 km). If you poured all of the world's water on the United States and could contain it, you'd create a lake 90 miles (145 km) deep.

This seems, and looks, like a lot of water, Gallo told Life's Little Mysteries, but looks can be deceiving.

If the Earth was an apple, Gallo said, the water layer would be thinner than the fruit's skin.

The Earth's freshwater is even rarer.

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