Shannon Airport is 25 km west of Limerick city, with direct flights to most major European cities and a handful of transatlantic routes (notably to Boston and New York). It is the easiest gateway to the west of Ireland. Frequent buses (route 51) connect the airport to Limerick city centre in around 45 minutes; taxis are 25-30 minutes.
By train, Irish Rail runs an Intercity service from Dublin Heuston in around 2h 15m; trains from Cork (1h 45m) and Galway (2h) connect via Limerick Junction. The bus network is denser — Aircoach and Bus Éireann run hourly services from Dublin, Cork, Galway, and Killarney to the central Colbert Station near the river.
By road, Limerick sits at the junction of the M7 (from Dublin), M20 (to Cork), and N18 (to Galway). The Limerick Tunnel under the Shannon makes the northern bypass fast; allow 2 hours from Dublin.