Improvements in the design process as applied to ocean structures have received intense interest in recent years. Part of this interest stems from the growing realization that design on a purely deterministic basis is inadequate for structures sub- ject to random loads, which are best described by statistical (or probability) methods. This book is an attempt to bridge the gap between present design practices and available analytical techni- ques (which may be exploited to improve present procedures). The book itself is an outgrowth of a set of notes prepared for an intensive short course presented over the past three years by the Engineering Extension Division of the University of California at Los Angeles, California. The ensuing presentation is composed of four parts. The material begins with a review of the physical environment (winds, surface gravity water waves and currents) for which engineering- type formulations are presented. Hindcasting and forecasting techniques using spectral concepts are included. Special problem areas are enumerated.