This castle is centuries old, has beautiful grounds, and makes for a great afternoon. Don't forget to kiss the Blarney Stone if you visit!
Fota Island is a nature preserve, with a full walkable nature park with all kinds of animals and gardens with plants form all over the world.
Cobh is the last place the Titanic stopped before her first trip across the Atlantic. There is a Titanic museum in the town, but also a quick ferry ride to Spike Island, another prison in Cork harbor that has a great walking tour.
A very historic site and a former prison; Cork is known as "the Rebel County" in Ireland for anti-British activities in the 20th century.
Yet another prison (told you Cork was the rebel county), this island is a quick ferry ride from Cobh, and offers guided tours.