A diver, a sump, a million years
Crag Cave
The entrance had been known since the 1850s — the Geological Survey of Ireland mentioned "caves worn by water" — but no one could get past the flooded passage they called the Green Lake. In 1983, a Welsh cave diver named Martyn Farr put on his kit, swam the sump, and surfaced in a chamber no one had ever seen. By 1985 the surveyors had mapped 3.8 kilometres of it. The Geaney family, on whose land the cave sat, opened 350 metres as a show cave in 1989. It's still in the family.
Con Houlihan's line
The longest village in Ireland
The Castleisland main street is famously long. Long enough that the locals call it the longest village in Ireland, and the joke has been around for so long it's nearly a fact. Con Houlihan, the great Kerry sports journalist who grew up in the town, put it best: "not so much a town as a street between two fields". The shape comes from the way the town grew along the road rather than around a square. There is a square — at one end — but the street is the thing.
The fortification that gave the town its name
The 1641 castle
Geoffrey de Marisco — Lord Justice of Ireland under Henry III — built a castle on the island in the river in 1226. It stood for four centuries, changed hands during the Desmond rebellions, and was finally destroyed in 1641 during the wars that followed. What's left is a stump of tower at the western end of the town, on the Killarney road. You can stand beside it and read the sign and that's about all there is to do, but it's the reason the town is called what it's called.
How the town keeps time
The Tuesday mart
The cattle mart in Castleisland has been running for generations and still sets the rhythm of the town's week. Tuesday morning the lorries come in, the pubs do early lunches, the bookmakers and the agricultural-supply shops do their best business of the week, and the talk in every queue is bullocks and beef prices. It's not put on for visitors. If you want to understand a Kerry market town, come on a Tuesday before noon.