Mt. Everest is considered the tallest mountain in the world at 8,848 meters above sea level. In fact, the largest mountain in the world is Mauna Loa, in Hawai’i. Mauna Loa rises 4,170 meters from sea level to the top of the summit, but its base is deep under water. The base of the mountain is at −5,000 meters. A probe is dropped 7,500 meters straight down into Mauna Loa from its summit.