Fully procedural water for Cycles. Realistic and highly customizable for full creative freedom.
Keep in mind that the caustics are based on the shadow ray, the texture used for created the shape act like a mask that let the light pass or block it. The more the caustics will be depth, the more they will be blurred (related to the penumbra shadow effect). So if you want sharp and realistic pattern, you have to keep your scene dimensions pretty low.
This file already contains an HDRi background find on this site : http://adaptivesamples.com/tag/hdri/ . It also contain another sky nodegroup for basic ambient lighting purpose.
Hope you enjoy, good blend! ;)