Ireland is a small country, divided into Northern Ireland, which politically belongs to the United Kingdom, and Southern Ireland, the Republic of Ireland. Another way to divide the island are the 26 counties of Ireland and 6 counties of Northern Ireland. For statistical reasons they are grouped into eight regions. Historical Ireland was divided into four provinces, cúige, which were Leinster, Munster, Connacht, and Ulster.
Originally we decided to group the listed locations by their geological background, but the geological situation is rather complicated and not very helpful. So we now list them by county, but we list only the counties with underground sites. We also list the most important karst areas. showcaves.com follows political borders for a simple reason: tourists travel to a certain country and often its not possible to cross borders without special documents like visa. In this case we think it's simple to visit the whole Ireland despite Brexit, while other parts of Britain require at least a ferry ride. So this "Ireland" we list here, is the island Ireland, not the country.