Prison island is the northern most part of the Empire of Pire...The 100 sq mile island is the main prison colony for political, military and civilian enemies of the Empire.  The Empire built one main facility that serves as living quarters and shelter for the island's inhabitants.  One a prisoner is air dropped onto the island...there is no escape...Air patrols guard the sky above the island, which is restricted air space.  Water approach is impossible thanks to electricified underwater fences and electro-magnetic devices that destroy all machinery.  Food is air dropped onto the island once a week.  Society on the island is truely survival of the fittest...