Spike Island is a 42-hectare island in Cork Harbour, almost entirely taken up by an 18th-century star-shaped bastion fort, now called Fort Mitchel. It started as a monastic site, but its position in the harbour made it a natural fortress, and for long stretches it was also a prison, holding convicts awaiting transportation and, later, Irish republicans. Along with Cobh it stayed a British base as one of the Treaty Ports until 1938.
Since 2010 it has been developed into one of the best heritage sites in the country, and it was named top European tourist attraction at the 2017 World Travel Awards. Boats leave from Kennedy Pier in Cobh, daily from April to October and at weekends in February, March and November. The ticket covers the ten-minute crossing, a 40-minute guided tour and about three hours on the island; it was €28 for adults in 2025.