Based on potential theory, the wave loads on a large-scale noncircular cylinder can be identified from monitored wave elevation data. In this chapter, a nonlinear method for wave load identification is presented. Expressions with underdetermined coefficients of quadratic transfer functions are formulated for the noncircular cylinder. The linear wave forces, second-order wave forces, and hydrostatic forces acting on the cylinder are identified. A comparison between the experimental and identified results of wave forces demonstrates the effectiveness of the identification method for a quasi-elliptical cylinder.