The sudden arrival of a harbor wave in a crowded seaport has terrified coastal residents for centuries. Tsunamis are among the deadliest natural catastrophes, in some cases killing thousands of people in a matter of minutes. Readers will learn how tsunamis develop, what kinds of damage they cause, and how scientists are using warning systems to give people more time to flee disaster. Some of the deadliest tsunamis in history, including the 2004 Indian Ocean tsunami, are also discussed.