With the increasing demand for marine structures (e.g. ships, platforms and wave energy devices) to operate in energetic, high sea states, there is a strong need for modeling and simulation of nonlinear ocean waves and dynamical stability of structures in these wave fields. To address this problem experimentally, a number of large-scale wave basins have been placed into operation over the last few decades, with a few larger and more sophisticated new ones under planning and construction. In this presentation, the current state of practice and technical issues in modeling and simulation of high sea state ocean waves are summarized. A novel methodology for quantitative evaluation of the suitability of competing linear and nonlinear wave theories for a given wave field with multi-spatial measurements is presented. Preliminary results of an on-going study on wave modeling and analysis of measured data from a wave-simulation performance study of the Oregon State University directional wave basin are presented. Nonlinear wave theories and solution procedures including inverse-scattering of the nonlinear Schrödinger and KdV equations, nonlinear Fourier analyses and nonlinear wavemaker theories are under development. The presentation concludes with a discussion on the mathematical tools required to systematically model nonlinear ocean waves and nonlinear wave generation in large-scale basins.