The term lagoon is derived from the Italian laguna, which originally referred to the waters around Venice but currently denotes a variety of geomorphologically and ecologically defined systems, including atoll lagoons and coastal lagoons. While the former are restricted to tropical latitudes, coastal lagoons are common features of the coasts of all continents, occurring, as they do, along about 13 percent of the worlds shorelines. This book reviews the geology, characteristics and diversity of coastal lagoons.