Wanderlust World Wanderlust World The Mid-Atlantic Ridge is the massive underwater mountain range that marks the divergent boundary between the North American and Eurasian tectonic plates. Stretching over 16,000 km (10,000 miles), it is the longest mountain range on Earth. As the plates pull apart, magma rises, creating new oceanic crust through seafloor spreading. This process slowly widens the Atlantic Ocean and pushes the continents apart at about 2–5 cm per year.