In the novel I'm writing, there is an island that sinks below sea level and rises up again at a later date. How is it possible to do this, while both keeping the surface of the island dry when it rises above the sea, and also to keep it connected to the mines beneath?
The island must sink and rise via a man-made method. The island raising and falling must be mechanical, with pistons or some kind of mechanical elevation or something, since it's activated by someone. It cannot be natural.
(Note: Quantum forcefield technology exists in the universe of my novel, which is essentially a barrier that prevents matter from passing through it, but it cannot lift or push anything since it has no force behind it. )