Inperushima, the Great Jail, is The Warning Lands Government maximum-security prison for the most dangerous criminals and ninja's. It is located underwater in the middle of The Warning Lands. The only way to get there with the greatest of ease, one must use a water current accessible by going through the Gates of Justice located at either the Marine Headquarters or Hōkishima. Also, the only way to safely get to the prison is to use one of the seastone lined Marine battleships as the entire place is surrounded by Sea Monstrers.