This image is the product of a forum discussion on the DAZ3D website about making underwater scenes in Iray. User William Timmins provided some general tips for constructing underwater scenes; I used his recommendations as a starting point for my own Iray underwater scene recipe.
While looking through my hard disk recently, I came across my original test scene, and decided to make something of it. I eventually came up with this scene, which adds a few figures, but doesn't otherwise change the test scene. The Great Kraken figure has been re-textured, to make its skin greenish and scaly rather than pink and shiny, and the minisub (actually an aircraft) in the foreground was changed from white to yellow.