Earth is an ocean planet. More than 70% of its surface is covered by
ocean with an average depth of just over two miles. But how much water is there really?
In this illustration, the sphere on the left represents Earth with all of the water removed. The
blue sphere to the right shows the approximate volume of all of Earth's
water. The tiny blue dot on the far right represents the available
Another way to think of it is that if we represented the size of Earth
with a basketball, all the water on the planet would fit into a ping
pong ball and the available fresh water would be smaller than a popcorn
kernel. Despite being such a water-rich planet, drinking water is one of
our most precious resources.
(Illustration by Jack Cook, Woods Hole Oceanographic Institution)