i would start with Water Surface Overview | Live Training and check out the water planes project on the learn tab of the launcher. Im not 100% on if you could use the materials from those in a game you sell but it will help you to learn to make your own material. as for the god rays its not something im totally familiar with but i would think you could accomplish it by having your ocean material translucent or masked. that way the light could still pass through and from there it would be like creating any other god ray.