In the ?rst edition of this book (publishedby Kluwer Academic in November 2000) the methodology of dynamical systems theory was introduced and appli- ̃ cations of this theory to the large-scale ocean circulation and El Nino were p- vided. Surprisedby the favorable reactions, I decided to make a second edition of the book which could be more easily used as a textbook for a graduate (700-level) course. The ?rst edition has undergone a substantial rewrite on three aspects: (i)thetext has been adapted at manylocations to improve clarity and readability, (ii)many recent results on thewind-driven ocean circulation, thethermohaline ̃ circulation and El Nino have been included, and (iii) a number of exercises have been added at the end of each chapter. In chapter 1, the description of what is known from observations on the global ocean circulation has been improved by including, for example, recent estimates of transport quantities. Both thechapters 2 and 3 have only slightly changed; in chapter 3, the text on homoclinic orbits has been extended as these type of phenomena have now clearly been found in the wind-driven double-gyre ocean circulation (as presented in chapter 5). In chapter 4, I have added a paragraph on the computation of isolated branches of steady states and the text on the iterative linear systems solvers has been shortened.