The Amazing Planet Earth
From the highest mountain peak to the deepest ocean trench, the surface of the Earth spans a total of 12.3 miles (19.8 kilometers) of vertical distance. The highest point, atop Mount Everest, is 29,029 feet (8.9 km) above sea level. The deepest point, the Mariana Trench in the western Pacific Ocean, is 35,814 feet below sea level (10.9 km).
Source:LiveScience