What Would Happen If All of the Oceans on Earth Were Drained at the Deepest Point of the Mariana Trench

As part of their ongoingWhat If?"series,Randall MunroeofxkcdandHenry ReichofMinutePhysics explained what would happen if a circular portal 20 meters in diameter appeared at the bottom of Challenger Deep in the Mariana Trench, known as the deepest known point on Earth, and began to drain all the water. The answer, at first, is not much.

It would take hundreds of thousands of years for the ocean to drain. Even though the opening is wider than a basketballcourt and the water is forced through atincredible speeds, the oceans are huge. The water level would drop by muchless than a centimeter per day. There wouldn't even be a cool whirlpool at the surface 'cause the opening is too small and the ocean is too deep.

If the portal grew exponentially in size, it would present a much more immediate problem that would grow greater and greater over time.

Great Britain, Sri Lanka, New Guinea, Java, and Borneo are now connected to their neighbors. And after 2000 years of trying to hold back the sea, the Netherlands is finally high and dry (some of dikes they built would now hold *in* the sea, rather than holding it out)As world experts on reclaiming land from the ocean, now that they're nolonger preparing for the constant threat of a cataclysmic flood.