The newer tunnels were fitted with these fluorescent lights, although some skylights (block glass embedded in skywalks) let in some natural light during the day.
Tunnels interconnected all of the complex, carrying power, steam, laundry and food throughout the hospital. This is a typical causeway that would have been very busy when the hospital was operating. In some places, signs still point to defunct areas of the hospital.
This is an elevator to move mine car loads of sand to the surface for cleaning and eventually glass production. Below is a flooded equipment vault. In front and behind is a loop through the larger tunnels in the mine. The horizontal braces supported electric cables for the mine carts.