Book excerpt: This book describes the latest developments in the hydrodynamics and morphodynamics of tidal inlets, with an emphasis on natural inlets. A review of morphological features and sand transport pathways is presented, followed by an overview of empirical relationships between inlet cross-sectional area, ebb delta volume, flood delta volume and tidal prism. Results of field observations and laboratory experiments are discussed and simple mathematical models are presented that calculate the inlet current and basin tide. The method to evaluate the cross-sectional stability of inlets, proposed by Escoffier, is reviewed, and is expanded, for the first time, to include double inlet systems. This volume is an ideal reference for coastal scientists, engineers and researchers, in the fields of coastal engineering, geomorphology, marine geology and oceanography.