Gaelforce Great River Swim

The Gaelforce Great River Swim is Ireland's premier downstream open water swim and the opening leg of the Gaelforce Great Swim Trilogy. Held annually on the River Shannon at the Roscommon–Longford border, the 2026 edition takes place on 16 May. Four distances from 800m to 12km follow the Shannon's current downstream to Lanesborough, making it one of the fastest open water swims in Ireland — and one of the most unique, with the river doing much of the work.

This is a downstream swim, which means the current is with you the entire way. The Shannon's flow carries you along, so your actual swimming effort goes further than it would in still water — first-timers are often surprised by how fast they cover ground. Water temperature in mid-May typically sits around 11–15°C (the 2025 event recorded an unusually warm 18°C). The river winds through open countryside with bends and turns, particularly on the 5.8km and 12km routes. Wetsuits are optional for distances up to 5.8km, with separate prize categories for wetsuit and skins swimmers. For the 12km, wetsuits are compulsory if the water is 11°C or below. Tow floats are mandatory for all swimmers in all distances. The safety setup includes rescue boats and kayakers along the full course. Swimmers who miss cut-off checkpoints are removed from the water.

Registration is through gaelforceevents.com. Entry fees range from €59 (800m early bird) to €160 (12km last chance), plus a €6 booking fee. Standard pricing for the shorter distances is €70–€80. On-the-day entries are available for distances up to 5.8km at a premium (€95–€100). The 12km requires advance registration only. Early bird pricing closed in October 2025. The event does not typically sell out, but the 12km has limited capacity.

The finish line is on the riverbank at Lanesborough, Co. Longford. Shuttles transport swimmers upstream to their distance-specific start points. Event parking is included in your entry fee and is located at the finish area. Lanesborough is about 1.5 hours from Dublin via the M4/N4 and roughly 1 hour 40 minutes from Galway. Accommodation in Lanesborough is limited — Longford town (20 min) or Roscommon town (25 min) have more options. Book early as the May bank holiday weekend can fill up.

The Great River Swim kicks off the Gaelforce Great Swim Trilogy. It's followed by the Great Lake Swim on Lough Derg in July and the Great Fjord Swim in Killary in September. Completing all three earns a Trilogy finisher medal plus an exclusive towel robe for 2026 entrants. The Glendalough Swim (May) and Malahide Friday Night Swim Series are also excellent early-season open water events if you want to build distance before the summer.