Charybdis by William Pye is an installation with a spinning vortex that can be observed from multiple levels.
About the piece:
The sirens Charybdis and Scylla resided in the Sicilian Sea. Homer tells us that because Charybdis had stolen the oxen of Hercules, Zeus struck her with a thunderbolt and changed her into a whirlpool whose vortex swallowed up ships. In Charybdis the circular movement of water inside a transparent acrylic cylinder forms an air-core vortex in the centre. Steps wrap around the cylinder and allow spectators to view the vortex from above.
How it works:
An air-core vortex is generated within a circular dish. Water rises and falls within the dish in a cyclic program of water activity. When the system is full and flowing over the perimeter and down the sides, the top surface is comparatively flat and smooth, only broken by the vortex in the middle. However, as the level drops, the body of water seems to take on a life of its own, increasingly rocking and swaying as its volume diminishes unaided by any outside force.