MOUNTAINS:
Mount everest is the tallest mountain in the world and is 29,029 feet. But If you add what's underneath, then Mount Everest isn't the tallest mountain. The winner then is Mauna Kea, a huge, very tall volcano on the Big Island of Hawaii (called Hawaii). Mauna Kea stretches 13,796 above water and 19,680 underwater, for a total of 33,476!
