Tsunamis, storm surges, and extreme waves are some of the hazards that can affect the inhabitants of coastal communities throughout the world, potentially turning into disasters if various unfavourable circumstances occur simultaneously. Such extreme events have a wide range of return periods, from tsunamis which can occur once every hundred or thousand years, to storm surges and extreme waves that can affect coastal zones of the world almost every year. Chapters 2 and 3 of this book provide a more detailed account of some of the major events that occurred in recent times, with a general explanation of these three different types of hazards being provided below. It is important to note that the study of such events is not only important to understand how to protect coastal areas, but can also inform the study of other sudden extreme hydrodynamic events, such as glacial lake outburst floods in countries such as Bhutan (Section 9.2). Also, it should not be forgotten that communities located at river mouths can also suffer from fluvial flooding (and the problems that cities in Tanzania suffer due to such events are detailed in Section 9.7). Thus, while the main focus of the present book is on coastal hazards, it is crucial to remember that these extreme events do not happen in isolation, and that there is a wide interdependency between different types of phenomena, forcing a disaster risk manager to think holistically and consider all aspects of such occurrences. By doing so, it is possible to increase the overall resilience of a given community, which can ensure it performs better against future hazards and ensure the long-term sustainability of the socio-economic environment it supports.