What is the name of the vast underwater mountain range that circles the globe?

The vast underwater mountain range that circles the globe is the mid-ocean ridge system. It is a connected network of underwater mountains extending through the world’s ocean basins, making it the longest mountain range on Earth.

Mid-ocean ridges form at divergent plate boundaries, where tectonic plates move apart. Magma rises from the mantle into the gap, cools, and solidifies as new oceanic crust. This process, called seafloor spreading, continually creates portions of the ocean floor and pushes older crust away from the ridge.

The global ridge system resembles the seam of a baseball and is roughly 65,000 kilometers long along its continuous mountain chain. Its total ridge-system length is often estimated at about 80,000 kilometers. Hydrothermal vents along some ridges support ecosystems powered by chemical energy rather than sunlight.

The Mid-Atlantic Ridge and East Pacific Rise are major sections of this worldwide system, not alternative names for the entire range. The Andes are a continental mountain chain, so they are unrelated to the global underwater ridge network.