The synthesis of realistic natural scenes in real time is one of the most important research areas for applications in games and simulators. In the beginning of real-time computer graphics, most of the applications treated water surface as a textured plane. This approach produces a very low realistic rendering of the water surface and does not reproduce the correct hydrodynamics behaviour of the water. So, a lot of research groups developed techniques for realistic water rendering, most of them for off-line processes and a few for real-time use. However, current improvementson hardware performance allow the usage oftraditional off-line techniques for real-time proposes, but there is no research work that describesthese techniques and makes a comparative analysis of them. Then, without this comparative analysis, it is very difficult to choose the best technique for a specific hardware or to decide if a particular technique provides the simulation control that a certain application needs.In this context, the present research work analyses the most important techniques for real-time ocean water simulation and visualization using the graphics processor unit as a main processor. Moreover, it makes a performance comparative analysis of each technique and analyses the pros and cons of them. Furthermore, some classic off-line methods are adapted for GPU use.