Lough Derg has no train station and minimal public transport. The practical way to arrive is by car or, for those following the Shannon system, by boat.
By car: The Clare shore is reached via the N18 from Limerick or Galway, turning east onto the R352 at Scarriff or Tuamgraney. Mountshannon is about 50 kilometres from Limerick (50 minutes) and 80 kilometres from Galway (1 hour). The Tipperary shore is reached from Nenagh, which is on the main N52.
By bus: Bus Éireann serves Killaloe, at the lake's southern end, from Limerick (route 343). From Killaloe you can cycle the Lough Derg Way northward along the Clare shore. There is no regular bus service to Mountshannon or Whitegate.
By boat: Lough Derg is part of the Shannon Navigation, and the lake's marinas — at Mountshannon, Dromineer, Garrykennedy and Killaloe — are accessible to cruisers coming from Portumna to the north or from Limerick via the lower Shannon. Hire cruisers can be picked up at Portumna or Killaloe.