Crepuscular Rays

Crepuscular Rays (A.K.A God rays) are a great lighting technique that take advantage of the environment. They are streams of light that pass between objects. They have a certain density that normal lights do not have. They are mostly used to show light that comes thought a window or between building, but they are also used for sunlight that is under water. This was used in notable movies like Finding Nemo and Pirates of the Caribbean. These add realism and atmosphere and help create a light source that can light an entire scene. The best part about god rays is that there east to make. All it requires is a point light that has a higher density in the middle then the sides and then placing it in the right place. This is the beauty of the god ray. 

Article: http://tigerprints.clemson.edu/cgi/viewcontent.cgi?article=3047&context=all_theses