An area of the Atlantic Ocean floor, known as the mid-ocean rift, is full of cracks, sometimes 2,400 meters deep. As a result, water seeps through the earth's crust down to its molten core. This heats the water, causing it to rise back up to the ocean. When it hits the cold ocean water, a cloud is formed. These hot-springs, called hydrothermal vents, can reach 371 degrees Celsius.