Mount Everest is best described as the highest mountain in the world. In other words: it has the greatest elevation, at more than 29,000 feet (about 8,850 meters) above sea level.
Other mountains, though, have made claims on being the tallest when measured from points other than sea level. Chimborazo in Ecuador, for example, has been cited as the tallest peak when measured from the center of Earth. At more than 20,000 feet (6,000 meters) in elevation, it falls short of Everest. But Chimborazo is located near the Equator, where Earth bulges, which means that it is about 6,800 feet (about 2,070 meters) farther above Earth’s center than Everest. All in all, Chimborazo reaches nearly 4,000 miles (6,400 kilometers) above the center of Earth.
Measured from base to peak, Hawaii’s Mauna Kea, which originates at the bottom of the ocean, is far taller than Everest, at about 33,500 feet (10,210 meters). Measured from sea level, Mauna Kea reaches only about 13,800 feet (4,200 meters).