Durgesh Prison is a location within Kyrat in Far Cry 4. Referred to as "The Sky Prison", it is a prison camp built into the side of a sharp mountain. Run by Pagan's second-in-command Yuma Lau, many local Kyrati are sent here against their will, never to return. Durgesh prison was built to imprison a guru whose prophecy once upset a great Kyrati king. Durgesh Prison is located in of North Eastern Kyrat. It is only accessible during the mission Don't Look Down, or through the Escape from Durgesh Prison DLC.
In the campaign you have to go into the prison and craft a "grappling hook" and make your way down the mountain; after you escape, you collapse and see a possible "Yeti". Then you find yourself at Ghale Homestead with Sabal or Amita at the end of the mission.