Art by Sam Burley, for the Subterranean Press edition of Iron Gold.
Deepgrave is a mobile prison located at the bottom of Earth's oceans. It was established in the fourth century of the post-Conquering era to house The Society's worst - murderers, rapists, terrorists, political prisoners, and war criminals.
After The Rising, Mustang banned capital punishment. Henceforth, all war criminals, oppressors, slavers and murderers who were captured by Darrow received life sentences in Deepgrave instead.
The prison is shaped like a crab, its huge shell littered with lights, intake vents and docking stations. The shell sits atop barnacle-covered hydraulic metal legs, which drag the prison along the ocean floor, constantly on the move.
The warden of Deepgrave in October 753 PCE was a Copper named Videli cu Yancra