Tsunamis are one of nature's most powerful forces, yet they are one of the least understood.
Usually created by undersea earthquakes and volcanic eruptions, these killer waves can race across entire oceans at more than 600 miles an hour and swallow entire cities whole, leaving thousands dead. Japan, Hawaii, and the Pacific Northwest have, throughout history, been struck by these destructive waves.
Heart-stopping footage and stories of survival illustrate how catastrophic a tsunami can be.
National Geographic joins scientists as they study this elemental killer and work to better prepare us for and protect us from nature's fury.