The earth is 8,000 miles wide. The deepest oceans? About 7 miles deep. If all the water on earth were rolled into a ball, it would cover an area that looks like this. The amount of drinkable fresh water would amount to a tiny fraction of total water.
DEM of Mars rendered with jDem846. Using the MRO MOLA 128 pix/deg elevation dataset overlayed with satellite imagery from the Celestia Motherlode. Elevations are exaggerated to enhance the visibility of terrain features. / by Kevin Gill