Stories about giant waves have been circulating among sailors for centuries, but skeptical scientists thought they were about as common as mermaids. Then, in 1995, an oil platform in the North Sea was hit by a big one during a huge storm, and it had the equipment on hand to determine that the wave had been a massive 84 feet tall. A few years later, a 95-foot wave was measured by a research vessel west of Scotland. Oceanographers realized that not only were these massive waves real, they were surprisingly common. According to the U.S. National Oceanic and Atmospheric Administration, rogue waves are more than twice the size of surrounding waves (often getting as big as 100 feet tall), come from surprising directions, and only happen in open seas.
If you think these facts about Earth are surprising, wait until you read about the strangest mysteries about planet Earth.