ABSTRACT
This chapter reviews the number of atolls found in each area of the world, 475 in total, lists the largest and deepest atolls, those with pronounced seagrass and mangrove areas, reticulated lagoons, and blue holes. We also list atolls that have been modified or used in other ways for military purposes, those with high population densities, and examples that are privately owned. This chapter ends by briefly describing the pronounced challenges that atolls are facing this century. Atolls are especially sensitive to water and food limitations. Water losses due to storm overwash, drought, overuse, and/or contamination by increasing populations are discussed, as are issues of erosion and some methods employed to counter the impacts of sea-level rise and storms.
