When you think of Earth’s great mountain ranges, you probably picture the Himalayas, the Andes, the Rockies. None of them are even close to the biggest. The longest mountain range on Earth is one almost no one has seen, because it lies underwater.
The Mid-Atlantic Ridge is a chain of underwater mountains running roughly down the middle of the Atlantic Ocean, from the Arctic past Antarctica. It connects to other ridges across the Pacific and Indian oceans, forming a single, continuous, 65,000-kilometer-long mountain system that wraps the whole planet like a giant seam.
It’s also where new seafloor is being made. Molten rock leaks up between Earth’s tectonic plates along the ridge, hardens, and slowly pushes the plates apart. The Atlantic is growing about an inch wider every year because of this - and that growth happens right at the spine of the world’s longest mountain range.
