Wow! I agree thats almost like the special effects they use in movies to make you feel like your falling. Or to make people entirely to dizzy for their own good. Congrats and don't get caught up in the dark mysterious ways because it looks like once you fall in theres no getting out.
Very nice design. Usually people make these tunnels seem quite attractive, but your colours really give this an atmosphere that threatens - well done. It is a little jagged in places, but not too bad. Great sense of depth.