Rogue waves are waves that are considered unusually large for a particular region or "sea state," and they usually occur far out at sea. They can be especially dangerous to ships, even large cargo ships or cruise liners. They can also happen on lakes, and numerous ones have been reported in Lake Superior, Lake Ontario and other areas of the Great Lakes.Rogue waves can reach enormous heights. One of the most famous incidents involving a rogue wave happened on Dec. 13, 1978 with the German ship MS Munchen. The cargo ship was in the North Atlantic when it issued a distress call and moments later vanished. An investigation concluded that a rogue wave between 80 to 100 feet high hit the ship, likely breaking it into pieces and causing it to sink, killing all 28 crew members. "Rogue waves can be impossible to predict because no one seems to know exactly what causes them," Panchang says. "We do know they can reach 100 feet high and perhaps even higher than that. We try to predict wave conditions that we know about, and where the data is in more of a controlled state. "When Hurricane Katrina hit in 2005, it rewrote much of what we had believed about waves," he adds. "It produced conditions that we did not think were possible, but it gave us critical new information about wave structure and movement. "In the past, some waves were called 'hundred-year waves' because it was believed that such waves only occurred every 100 years or so. But the hurricanes of the past decade or so have shown us that is not true – they can occur much more often. They have given us information that allows us to give more precise models about waves and how strong and high they can be."