Irish triathlon is a small scene with a disproportionate number of genuinely hard races in it. There is no flat, fast, warm-water event of the kind that fills a European calendar — what there is instead is mountain passes, Atlantic swims and a governing body that takes water safety seriously for reasons the sport here has had to learn.
The water
Start here, because it constrains everything else. Irish sea temperatures peak somewhere around 15-17°C in August and fall away quickly either side. That is comfortably inside wetsuit-legal territory under every federation's rules, and in practice a wetsuit is worn at essentially every Irish triathlon regardless of distance.
The lakes are colder than the sea, not warmer, because they are mountain-fed and shallow enough to lose heat fast. A swim in the Lakes of Killarney in late August is a colder proposition than the sea at Youghal on the same day.
The honest warning
The 2023 IRONMAN at Youghal saw two athlete deaths during the swim, and the 2024 edition was cancelled — Triathlon Ireland subsequently stated it had been unable to sanction the race on water-condition grounds. Whatever race you enter here, read the swim safety information properly rather than skimming it.
The races that matter
Hardman Killarney — August
Billed as Ireland's only full-distance triathlon: a 3.8km swim in the Lakes of Killarney, 180km through the Kerry mountains around the MacGillycuddy's Reeks, and a full marathon. An independent Irish event rather than an international franchise, which is much of its character.
The Lost Sheep, Kenmare — late August or early September
Middle distance, running since 2003, and widely regarded as the toughest race of its kind on the Irish circuit. A 1.9km swim in Kenmare Bay, then an 83km bike out along the Beara peninsula crossing the Lauragh, Healy and Caha passes, then a 21km run. Three mountain passes in 83km is what earns the reputation — the Healy in particular is among the hardest surfaced climbs in Ireland.
Hell of the West, Kilkee — late June
Olympic distance, and the oldest event of its kind in Ireland — running since 1985, with the 40th edition in 2027. A 1,500m swim in Horseshoe Bay, a natural harbour sheltered by the Duggerna Reef, then 44km into the West Clare wind and a hilly 10km along the Loop Head coast.
IRONMAN 70.3 Cork, Youghal — August
Ireland's half-distance IRONMAN, on the East Cork coast. A 1.9km sea swim off Front Strand Beach, a 90km rolling East Cork bike leg and a flat 21.1km seafront run. The most conventional of the Irish middle distances, and the flattest.
Lough Cutra Castle, Galway — late May
The outlier, and the one to start with. A weekend festival on a private lake in castle grounds near Gort, with triathlon, duathlon, aquabike, aquathlon, swims and runs at distances from beginner to elite. The swim is sheltered fresh water on private land, which removes most of the variables that make Irish open water intimidating.
Where to start
If Ireland is where you want to do your first triathlon, Lough Cutra is the obvious answer — a sheltered private lake, flat south Galway roads for the bike, an estate run, and beginner distances running alongside the elite ones over the same weekend.
What Ireland does not really have is the pool-based sprint that gets British beginners into the sport. The entry point here is open water, which is a bigger step, and it is worth doing some supervised open-water swimming before your first race rather than discovering the difference on the day.
Triathlon Ireland
Triathlon Ireland is the governing body, sanctions the domestic calendar and runs the national championships. Club membership works much as it does in Britain, and the club scene is the main route into the sport here — Irish triathlon is more club-centred and less commercially organised than the British equivalent.