Take this for example: How to breathe under water.
It's all fake!
http://www.behance.net/MatthewAlbanese/frameDiorama made out of walnuts, poured and cast candle wax, wire, glitter, peanut shells, flock, plaster, wire, dyed starfish, compressed moss, jellybeans(anemones), sponges, wax coated seashells, toothpaste,
clay, figs, feathers, Q-tips, nonpareils. Surface of the water was created using vinyl shower curtain, plexiglass and clear epoxy. The reflected sunlight effect was created using a video projector through fake fog. The white balance was set for tungsten allowing the sunlight to appear bright and clear while the strobes provided a deep blue shift in the fill light regions. The lens was covered with a piece of blue stretch wrap which created subtle distortions throughout the image. A total of 11 light sources were used including the projector.
There's loads more and all are amazing.