(Illustration by Jack Cook, Woods Hole Oceanographic Institution)
More than 70% of Earth’s surface is covered by ocean, with an average depth of just over two miles (a fairly shallow depth when compared to the diameter of our planet). 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 fresh water.
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.