The animation was my first idea and i also had a large chamber at the end of the tunnel. I've scaled it way back. I'm still deciding about the type, but when i switch to using multiple terrains for the walls and ceiling, i'm going to make it much blockier, like a man-made tunnel would look. I have some good reference material for that... except for the floor. I can't find any shots of man-made tunnel floors that haven't been tiled or otherwise finished. I may actually turn this into several images with different types of walls and ceilings. Thanks for taking the time and for your comments.