I checked this book out of a school library in the early 80's and it was really big and dusty then...it was about a people that lived on the surface of a water planet on living organic rafts. The elite undersea kingdom below, and a mysterious cylinder in space ...any help finding this book would be greatly appreciated B
It sounds like one of the books in the Destination: Void series by Frank Herbert and Bill Ransom. There are four books, Destination: Void, The Jesus Incident, The Lazarus Effect, and The Ascension Factor. My own personal guess is *The Lazarus Effect, as that seems to fit your question better. I seem to recall it had more of a class structure than the Wikipedia entry seems to imply.