Patterns in surface water waves Walter Craig McMaster University Abstract: I will describe an existence theorem for traveling waves in water. The first such in two dimensional settings is due to T. Levi-Civita and D. Struik in the 1920's. In a recent paper we prove a general result for three dimensions (well, for any number of dimensions), when there is surface tension. The approach is surprisingly close to the Lyapunov center theorem of A. Weinstein and J. Moser, using the fact due to V.E. Zakharov that the water waves problem can be formulated as a Hamiltonian system with infinitely many degrees of freedom. Without surface tension the problem exhibits small divisors, and is more difficult.