The calculated distance (air line) between Carrigtwohill and Dún Laoghaire is approximately 131 miles respectively 211 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Carrigtwohill and Dún Laoghaire has been calculated here.
Air line (approximately)
211 kilometers
114 nautical miles