The third volume of Water Science Reviews addresses the dynamics and transport of water at the molecular and macroscopic level. The study of the hydrated proton, by C.I. Ratcliffe and D.E. Irish, is a masterly survey of a complex subject, in which the authors concentrate on the vast literature dealing with the theory of solution chemistry. H. Levine and L. Slade develop the concept of water as a platicizer of natural and synthetic polymers. A. Deri Tomos considers the cellular water relations, including water fluxes at the level of the single cell. Finally, W. Pusch examines differential flows of water and selected solutes across synthetic membranes.