Where is the longest mountain range in the world?

The longest mountain range on Earth is almost entirely hidden beneath the oceans: the mid-ocean ridge system stretches about 65,000 kilometres, winding around the globe like the seam on a baseball. It forms where tectonic plates pull apart and molten rock rises to create new seafloor. On land, the longest mountain range is the Andes in South America, running about 7,000 kilometres down the western edge of the continent through seven countries. The Andes contain many of the highest peaks outside Asia, including Aconcagua at 6,961 metres, the tallest mountain in both the Southern and Western Hemispheres.