This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
A hopper was set to take medical personnel and their patients from an underground location where Kirby, Kalandra, Jake Sisko, and Julian Bashir were stationed to the base at Tananda Bay in 2373. The tunnel from the underground location to the surface was over two kilometers long, and they had over seventy patients at the time. A security detail was sent to defend the medical teams long enough for them to move the patients. (DS9: "Nor the Battle to the Strong")