Great River Swim, Ireland

Simon Griffiths swam 12km down the River Shannon with Gaelforce Events

The River Shannon owns the record for the longest river in the British Isles. Apparently, this is a useful piece of trivia for pub quizzes, but it wasn’t something I knew before I took part in the Gaelforce Great River Swim. It always surprises me what I learn from swimming.

The river is often referred to as “mighty” and I can well imagine it’s a force to be reckoned with when in spate. It drains around a fifth of the total land area of Ireland. But on 17 May this year, it was more majestic than mighty, its power hidden beneath a serene and soothing surface.

Gaelforce Events has run swimming events in the Shannon since 2023 but this was the first year they extended to the 12km distance. Around 85 of us signed up. We were in for a treat.

Wandering Ireland’s wild west

We entered the water in the village of Tarmonbarry, just downstream from Tarmonbarry Lock. It’s a picturesque spot. The river is around 100m wide, banked by reeds and surrounded by low-lying farmland. The water is a deep peaty brown colour and feels silky smooth to swim in.

The Shannon at Tarmonbarry has already passed through some 50 miles of Ireland’s heartlands. It’s mostly rural. Unlike the Thames, there are no major towns and their accompanying sewage treatment works. The water quality is excellent. One local assured me it was drinkable, although I didn’t put that to test.

Navigation was simple. Swim downstream until you hit Lough Ree, then turn left to finish. We were given the full run of the river and left to our own devices to choose the best line. I liked that. The only markers on the river were large buoys every kilometre, but these were just to help you keep track of distance not show the best line.

Fast swimming

River flow was low in 2025 as Ireland has had unusually little rain. But it was still noticeable. One of the joys of river swimming is covering the distance at faster than normal swimming speed and watching the banks glide by. The water was also unseasonably warm at around 18 degrees. If you do this swim another year, prepare yourself for cooler water and a stronger current.

The ease of navigation and the tranquil conditions made this one of the most relaxing swims I’ve done. The river meanders a little but generally heads south. It narrows and widens again, as rivers do. There are a couple of islands, too. I swam through it all in a contented flow state.

Approaching Lanesborough, you pass a decommissioned peat-burning power station. This incongruous building serves as a useful landmark. I think it was the only building I saw throughout the swim. If you have any energy left at this stage, you could try to speed up. Shortly after the power station, you swim under the N63 and Lough Ree opens up ahead of you. Arc around to your left and swim into the event village where volunteers help you out of the water. Your swim is over, but don’t rush off.

The festival

The first reason not to disappear as soon as you cross the line is that the finish area and event village are in a lovely location at the top of Lough Ree. There’s plenty of space to stretch out, relax and enjoy the view.

Stay to soak up the festival atmosphere, too. There’s a live band, local exhibitors and, importantly, food. Take a moment to get to know your fellow swimmers. What did they see that you missed, and vice versa. What other events do they recommend?

I enjoyed watching other swimmers finish. Whether they’ve done the 12km or one of the shorter swims (800m, 3.5km or 5.8km) everyone has something to celebrate. Some sprint for the finish in a tussle with a friend or maybe just someone they’ve been swimming next to. Others stop to enjoy the moment and check the views before they cross the line. It seems as if they’re reluctant to stop swimming. Some wave their arms in celebration. Others look as if they can barely lift the arms but their faces beam with pride.

Smooth operation

Overall, the Great River Swim was well organised. From bag drop off, registration and transportation to the start, everything ran smoothly and on time. The feed station at the half-way point on the 12km was well-stocked and easy to find. The team and volunteers were friendly and helpful. The festival encouraged swimmers and their friends to hang around and socialise. If you fancy a longish, early season swim in a lovely location, then add the Great River Swim to your list.

What else to do

My trip to the Great River Swim was supported by Tourism Ireland. Lanesborough, despite its stunning location at the top of Lough Ree, is not as well-known tourist destination as Ireland’s dramatic west coast. Yet it’s worth a visit and we could easily have spent more time exploring the area. In the little we had, we strolled along a pretty section of Royal Canal that connects the River Shannon to Dublin, visited the Corlea Trackway, which has the remains of an amazing Iron Age floating pathway across the peat bogs, and took in a couple of neolithic burial mounds.

We also spent an afternoon exploring part of the Wild Atlantic Way, looping around the amazing Killary Fjord, the location for one of Gaelforce’s other swims. It was a lot to pack into a weekend and our brief visit has left us wanting to go back for more.

Find out more:

Great River Swim: gaelforceevents.com/en/gaelforce-great-river-swim
Great Fjord Swim: gaelforceevents.com/en/gaelforce-great-fjord-swim
Great Lake Swim: gaelforceevents.com/en/gaelforce-great-lake-swim
Watch Simon’s interview with event organiser Mary Young:
Visit Ireland: Ireland.com