Chapter headings. Series preface. Preface and acknowledgements. Principal symbols. List of tables. Introduction. Some basic concepts and definitions. Measurement: omnidirectional. Directional measurement (in situ sensors). Analysis and interpretation: omnidirectional. Estimating extreme wave height. Analysis and interpretation: directional data. Remote sensing of waves. Waves in finite depth. Wave generation by wind, and wave forecasting. Nonlinear effects. Errors and uncertainties. Appendix 1 The computation of wave spectra. Appendix 2 The spectrum of the product of two random variables and that of the square of one random variable. Appendix 3 Cross-power Spectra. Appendix 4 Digital integration and filtering. Appendix 5 Some useful statistical formulae. Appendix 6 Fitting regression lines to wave data. Appendix 7 Initial analysis and on-line recording of wave data: practical recommendations. References. Subject index.