This paper presents a model for automatically generating 3D cartoon ocean water animations in real-time. The dynamic ocean water surface model is modeled by a spectral method. The cartoon rendering process is implemented by multipass on GPU: First, we code normal of ocean model and generate normal map. Next, we extract discontinuities from normal map and smooth it into edge map. Finally we combine the edge map with cartoon shading based on a projective texture mapping. Some experimental results demonstrate the prettiness and efficiency of the presented model.