Shiva Island

Shiva Island ( シヴァ島,  Shiva no Shima) often referred as The Forbidden Island (  禁断の島 , Akazuno no Shima) to the people of Wano Country, was once a government owned and protected island found in the new world. It was contract to be used as a research and experiment on curing the aliment and diseases of the age. However after Shiva had learned that his son was nearly beaten to death by a certain jester pirate, Shiva betrayed the Government. As of now the island is now believed to be abounded and the citizens of Wano Country claim the island to be inhabited by demons with strange armor and weapons. As the where abouts of Shiva still unknown, De Gama and the rest of his experiments scattered across the world.

Location
The island is located within the new world on the outskirts of Wano Country, the island is locate over an accent dormant volcano, in which Shiva's Compound is located in the middle of the volcano. However, by the rumors from Wano Country, the island is believed to be located between the human world and hell. Due to the fact that many creatures with strange armor.