All the environment materials use an Arch&Design shader. I highly recommend this shader, which has been part of 3ds Max since the 2006 version. It is really versatile for all kinds of situations. In this case, mostly of the surface shaders used a light blurred reflection to merge them all together.
If you want more information on the Arch&Design shader you can found a description of all the options available here.
For the character/pants/tentacles I rendered two passes (one with the SSS Fast Skin shader and one with the Arch&Design shader) and after that I composited them in Photoshop.
I took a screenshot of my water shader) since it was the most complex one (Fig.23). I recommend this excellent tutorial for creating the same kind of material with caustic included: Link 1 I Link 2