Tsunamis, the giant waves that periodically engulf coastal areas and even the shores of lakes and rivers, have had a major impact on the world. Not only have they caused countless deaths but also they have changed nations, societies, and cultures from prehistoric to modern times. This book describes the science of tsunamis and the many ways they can be generated, ranging from earthquakes to volcanic eruptions and explosions, landslides, and others. It also explains how the waves travel across oceans at the speed of a jet airplane and how they focus or disperse their incredible energy. It delves into the clues that ancient tsunamis have left behind to be unraveled by modern science so that we can better understand not only what has happened in the past but also what will happen in the future. The book also explores the human side of tsunami disasters, examining their effect on the residents of impacted communities by recounting the amazing true stories of survival, heroism, and tragic loss. It discusses and provides examples of what works in mitigation, preparedness, warning, response, and recovery from tsunamis; what does not work; and what needs to be done. It contains little-known stories about scientists struggling to better understand these catastrophic waves, while fighting government ignorance and reluctance to take action, as well as amazing chance discoveries and the continued quest to learn more and become better prepared, as every year the odds of yet another catastrophic tsunami increase.