On the morning of December 26, 2004, many coastal residents of northwestern Sumatra were startled as water at the shore dramatically receded below the normal low-water mark, leaving fish flapping on the exposed beach. The people drawn closer to the coast by this remarkable sight surely didn't know how to explain the water's bizarre behavior. Yet even in the early hours of the tsunami disaster, scientists began to grasp what was happening. In the following days, using maps of the seafloor and seismic data, tsunami researchers produced remarkably accurate computer simulations of the monstrous series of waves that took hundreds of thousands of lives. In this interactive, examine some of these models and other graphics that reveal details of the tsunami from its initial generation in deep water to its deadly collision with coasts around the Indian Ocean. To launch the interactive, click on the image at left.—Susan K. Lewis