The island off Ireland once hosted the world’s largest prison, holding over 2,300 inmates.

Spike Island, just stone's throw away from Cobh in County Cork, has a very dark past having once been home to the world's 'largest known prison', being dubbed the Irish Alcatraz.

It has now been opened to the public, so visitors can explore its eerie history which dates back more than 1,300 years.

In the ninth century it was ravaged by Vikings before becoming a monastic settlement until the 16th century.

Visitors can also follow the monks' pilgrimage path around the island.

Despite this, its most well-known use was its prison which began in the mid-1600s and saw thousands of prisoners detained during Oliver Cromwell's conquest of the country and the 1947 Famine.

Its star-shaped fortress which held over 2,300 prisoners gave it the reputation of the worlds largest prison until 2004 when it was shut.

Due to its off mainland status, it gained direct comparison to Alcatraz Island in California, however its fortress, Fort Mitchel, which still remains on the island, is so large it could fit the entire Alcatraz Island inside.

Additionally, today's visitors can explore the military Gun Park which holds tanks, cannons, and artillery.

Combine its scenic walking routes and history with a 15 minute ferry from Cobh and it makes for a solid day out.

A visitor wrote of the island on TripAdvisor: "Visited Spike Island at the end of November, and I found the history of the place thoroughly fascinating. Euan, our guide, was so passionate, enthusiastic, and knowledgeable. Well worth the visit."

"We had a very enjoyable and educational trip, our tour guide Euan was amazing, he was very entertaining and a font of knowledge, we were there for about 3 hours but would have liked to have spent another hour or two, we will definitely do a return trip," said another.