My first underwater scene, in cycles, using vomue scatter to create the halo effect and the ocean modifier (inspired by a german tutorial on youtube) for the caustic effect.
All textures are from free copyright image. I had to change the uv map of the orange fish because the original fish image was not copyright free, so I used an image of an another fish (sorry for that, so this fish does not exist in real life ;)
The texture for the shark was done by myself with gimp 2.8 (very easy and straightforward one).
I thank Szyko for the procedural sand texture (I wanted to uv the ground, but the Szyko material was well rendered so I use your material).
1024*1024 only 200 scans, it took more than 24 hours to render (damn it).
Hope you like it. (I also did a lobster that I originaly wanted to put into this scene, but I removed it as it would have been too much).