is underwater: the mid-ocean ridge
The longest mountain range on Earth is not the Andes or the Himalayas. It is the mid-ocean ridge system: nearly 65,000 km of volcanic mountains, more than 90% of them underwater.
The top of the ridge lies on average about 2,500 m below the surface. Drop the sea to 3,000 m and it appears: a mountain chain running down the middle of the Atlantic.
In Iceland the ridge rises above the sea. The island straddles the Mid-Atlantic Ridge and is slowly being pulled apart as North America moves west relative to Eurasia.
In the eastern Pacific, the East Pacific Rise spreads 6 to 16 cm a year. It moves so fast that instead of a deep rift valley it has a broad, smooth crest.
Laid end to end, the ridge system's 65,000 km would wrap around the equator (40,075 km) more than one and a half times.
Pull the plug and watch the sea level fall, explore the seafloor as real terrain, find what lies off your own coast, and follow guided stories, from the Ice Age land bridge between England and France to the wreck of the Titanic. Everything is built from GEBCO's grid of the world's ocean floor and land.
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