Goli Otok was once described as a "Living Hell" by those who were unlucky enough to be sent to the prison.

Lying just two miles off the coast of Croatia, the prison was less a place for petty criminals and more a dumping ground for prisoners of war and later political dissenters. During World War I, Austria-Hungary used the island to house Russian soldiers.

In 1948, as Cold War tensions began to rise, Yugoslavian leader Josip Broz Tito—a communist revolutionary—broke ties with the Soviet Union. Goli Otok soon became a political prison and labor camp for those in Yugoslavia who still supported Soviet leader Joseph Stalin or otherwise opposed Tito's rule.

Documents published by the Central Intelligence Agency in 1970 reveal that Tito's regime routinely collected political dissenters from 1948 to 1955 when the prison was most active. By 1956, more than 15,000 people were estimated to have been sent to the tiny island and as many as 600 may have died there—some allegedly from torture. The CIA report described the island as Tito's Adriatic "Devil's Island" and argued it was as much a prison for Stalin supporters as it was for those who dissented in Tito's regime. (Some also call it the "Croatian Alcatraz" because of its location on an island and high security.)

The prison closed its doors at the end of the 1980s, when the Iron Curtain began to crumble across Eastern Europe. At that time the Berlin Wall came down and the Soviet Union began sliding towards collapse.

Today, the island stands in ruins. Since its abandonment, the prison's remains stand as a haunting reminder of Tito's totalitarian regime. Little vegetation exists on the 1.5 square miles and only an occasional sheep can be seen roaming the island. The only human visits come from the occasional tourists seeking to explore the prison's ruins. (See other haunting relics from Yugoslavia.)

Bob Thissen is a Dutch filmmaker passionate about documenting and exploring remains like those at Goli Otok. In 2016, he traveled by private ferry to the island and filmed the decrepit remains.

"Walking among ruins... It's pretty creepy," he said in an interview with National Geographic. "You can see the high walls and the cells still there."

His video shows where the steel skeletons of mid-century buildings have collapsed. Tools and working tables still lay strewn about in abandoned workshops where prisoners were forced to work.

Thissen camped on the island overnight and described the lack of flora and fauna as eerie and quiet.