Area · Co. Clare
Lough Derg, the third-biggest lake on the island of Ireland, stretches 38.6 km across the Shannon basin. It hosts the pilgrim island of Inis Cealtra and offers cruising opportunities along its shores in Clare, Galway, and Tipperary.
Lough Derg sits in the Shannon River Basin. Historically called Lough Dergart, or Loch Deirgeirt in Irish, it is a freshwater body of water. On the island of Ireland, it ranks third in size after Lough Neagh and Lough Corrib. In the Republic, it is the second largest. The shape is long and narrow. You can navigate 38.6 km (24 miles) of it. The surface covers 130 square kilometres. At its deepest point, the water drops to 36 metres. Counties Clare, Galway and Tipperary share the shores. It is the southernmost of the three great lakes of the Shannon, the others being Lough Ree and Lough Allen. Towns and villages line the banks. Portumna, Killaloe and Ballina, Dromineer, Terryglass, Mountshannon and Garrykennedy serve as bases. They make the lake work.
The name comes from Irish: Loch Deirgdheirc. That is one of the names of the Dagda, the father of the gods in Irish mythology. It literally means “red eye”. The lake is best known for Inis Cealtra, also called Holy Island. A pilgrim tradition has been kept there for centuries. It is a small island in the middle of the water. The whole lake has been famous for it. The water is calm enough to work. It is wide enough to feel like a sea. The light on it in the late afternoon is the best of the Shannon.
This is a cruising water. It is navigable over its full length. Cruisers and slower boats are popular here. The shore villages are the way in. Grab a coffee in Killaloe or Portumna. Walk along the shore. If the boat is running, head to the island. Downstream, close to where the lough empties into the Shannon, you will find the Doonass falls. They are the largest fall on the otherwise gently sloping river. Nearby stands the Ardnacrusha hydroelectric plant. When it was built in 1927, it was the largest in the world.
Allow a day on the lake. Spend the morning in the shore villages. Take the afternoon for the island or a cruise. Pair it with the Shannon for the full waterway day.
Where to stay
Stay in Killaloe or Portumna and the lough, the island and the shore are all inside the day.
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Black Head is the north-western tip of County Clare, where the coast turns and a small 1936 lighthouse stands above Kilrush Bay. The headland offers views of Galway Bay and the Burren, with a concrete tower built after complaints from liner captains.
Carrigaholt is a small fishing village in County Clare at the mouth of the Moyarta, featuring a ruined castle and active pier on the Loop Head peninsula’s estuary side.
Doolin is a west Clare village known for nightly traditional music sessions and harbour departures to the Aran Islands, located four miles from the Cliffs of Moher.
Ennistymon is the market town on the Burren's eastern edge, defined by the River Inagh and its Cascades behind the main street. It sits at the junction of the N67 and N85, serving as a base for the karst country and the road to the Shannon estuary.