What is the longest mountain range on Earth?

The longest mountain range on Earth is the mid-ocean ridge, a chain of undersea volcanic mountains that stretches nearly 65,000 km around the globe. More than 90% of it lies deep in the ocean, where tectonic plates pull apart.

What's actually true

Earth's longest mountain range is almost entirely underwater. The mid-ocean ridge is a chain of undersea volcanic mountains that winds around the globe like the seam on a tennis ball. It stretches nearly 65,000 kilometres, and more than 90 percent of it lies deep in the ocean. It forms where tectonic plates pull apart and new seafloor is made.

Takeaway: The planet's biggest mountain range is one almost nobody has ever seen.

Why people believe it

Ask people for the longest mountain range and they name the Andes or the Himalayas, because 'mountain range' brings to mind peaks we can see, climb and photograph. Maps and globes usually show the ocean as flat blue, so the ridge is missing from the mental map most of us carry. It also does not look like mountains from above: it is hidden under kilometres of water.

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