Gaelforce Great Lake Swim

The Gaelforce Great Lake Swim is the second leg of the Gaelforce Great Swim Trilogy, held on the freshwaters of Lough Derg at Portumna, Co. Galway. The 2026 edition takes place on 11 July with three distances from 750m to 3.9km. Lough Derg is one of Ireland's largest lakes — open, exposed, and surrounded by small islands and ancient ruins — offering a very different challenge to the sheltered fjord or current-assisted river swims in the Trilogy.

Unlike the downstream River Swim, there is no current to help you here. Lough Derg is a large, open freshwater lake, and you'll need to sight-navigate across open water. The course is a loop starting and finishing at Portumna's swimming area. Fresh water is less buoyant than salt, which many swimmers notice — you sit slightly lower in the water and it can feel harder than a sea swim of equivalent distance. Water temperature in July averages around 12°C, though the FAQ notes it can be as low as 7–8°C depending on conditions. Wetsuits are optional with separate prize categories for wetsuit and skins swimmers, though the organisers recommend wetsuits for the 3.9km distance. Tow floats are compulsory for all distances. The safety setup includes kayakers, rescue boats, and a medical team.

Registration is through gaelforceevents.com. Entry fees range from €59 (750m early bird) to €85 (3.9km last chance), plus a €6 booking fee. Standard pricing is €70–€80. On-the-day entries are available at a premium (€95–€100). Early bird pricing closed in November 2025. The event does not typically sell out, but entries close when capacity is reached.

The event is based at Portumna swimming area on the shores of Lough Derg in east Co. Galway. Portumna is about 2 hours from Dublin and 1 hour from Galway city via the M6 and R446. Free event parking is included in your entry fee. Portumna has a handful of B&Bs and self-catering options, but nearby Birr (20 min) and Nenagh (30 min) offer more accommodation. July is peak tourist season in the midlands, so book at least a few weeks ahead.

The Great Lake Swim is the second event in the Gaelforce Great Swim Trilogy, sandwiched between the Great River Swim (May) and the Great Fjord Swim in Killary (September). Completing all three earns the Trilogy finisher medal. If you're looking for an open water race between the River and Lake events, the Glendalough Swim (May) offers a similar freshwater challenge in the Wicklow Mountains.