About 70 percent of our planet is covered with water. Including all seas and oceans, water covers about 140 million square miles of earth, with an average depth of 11,600 feet.
That means that the total amount of water on earth is 315 million cubic miles! If all the water on earth were spread over the planet evenly, it would cover all the land to a depth, of almost two miles.
Only mountains taller than about 10,500 feet would remain above the surface of the water!