A proper roasting day in Northern Ireland is a gift — don't waste it hiding indoors. Get in the water. Eight of these ten swims are completely free, and the sea is the best air conditioning there is.
The mix — one giant inflatable aqua park on a lake, a freshwater obstacle course, the great lifeguarded strands, and sheltered bays where the shallows do the babysitting. Every kind of swimmer is covered, from belly-floppers to length-swimmers.
Cost — eight of the ten are free (a couple charge for parking). The two aqua parks run about £25 a session and are worth every penny on a scorcher. Each entry links to our full guide with current prices and parking.
Flags first.Swim between the red-and-yellow flags — RNLI lifeguards patrol the flagged beaches in July and August (Cranfield adds September weekends, Tyrella runs through the main season). Off-season and off-flag, mind the tides and currents.
The aqua parks are pre-book only. Let's Go Hydro and The Lake at Kilrea run booked timed sessions that sell out in summer — and both have swim rules (50m unassisted at Hydro, 25m at The Lake). Book online before you set off.
Food — Harry's Shack on the sand at Portstewart, a tea room and pub two minutes from the water at Cushendun, chip shops and ice cream in Ballycastle, and coffee huts at both aqua parks. Swimming hunger is the best hunger.
When — the hotter the day, the better this list gets. Pack a hat, plenty of water and a patch of shade for the height of the afternoon, and you can go from first swim to last light.
1
Let's Go Hydro
Carryduff, Co. Down · From around £25 · Pre-booked sessions
Ireland's biggest inflatable aqua park, floating on a lake just south of Belfast — and on a roasting day there is no better place to be. Wetsuit and buoyancy aid on (both provided), then 50 minutes of climbing walls, a big slide tower, trampolines, monkey bars and glorious belly-flops. Falling in is the whole point. There's a gentler junior water zone for younger swimmers, a café on site, and lakeside glamping if one day isn't enough.
Allow half a dayFrom ~£25 · wetsuit providedPre-book only · age 7+, 110cm, swim 50m unassisted
Portstewart · Free to walk on · Charge to drive on the sand
The classic. Two miles of golden National Trust sand where you drive on, park beside your spot, and walk straight into clean Blue Flag water. Rolling surf for the boards, firm sand for the sprint in, and Harry's Shack waiting with chips when you come out shivering happy. RNLI lifeguards patrol in summer — swim between the red-and-yellow flags when they're on, and take real care with the tide and currents at other times.
Half a day or moreHarry's Shack · seasonal toiletsLifeguards summer only — swim between the flags
The one for small swimmers. A gently-sloping Blue Flag beach at the mouth of Carlingford Lough where the water runs warm, shallow and sheltered — the shallow water is the whole draw, with the Cooley Mountains standing across the lough. Toilets, showers, a play park and a free car park right by the sand. RNLI lifeguards patrol daily 11am–6pm through July and August, then September weekends — swim between the flags when they're up.
An easy 2–4 hoursFree, with free parkingLough-mouth tides — watch the incoming tide, keep paddlers close
Seven miles of golden Blue Flag sand under the Binevenagh cliffs — so much room that even on the hottest day of the year you can find your own patch. Drive on, park beside your spot, and swim: RNLI lifeguards patrol 10am–6pm daily in July and August, and the beach is zoned so swimmers get their own stretch. The Tourist Complex at the entrance adds outdoor heated splash pools in summer, plus a coffee shop.
2–4 hours, easily a dayFree, with free parkingLifeguards July & Aug only — swim in the flagged zone
Kilrea, Co. Londonderry · ≈£25 an hour · May–September
The inland answer to a heatwave: eleven acres of freshwater lake turned into a giant floating obstacle course — icebergs, balance bridges, wipeout balls, and The Beast, billed as the tallest floating slide of its kind in the world. Sessions run as booked one-hour slots, wetsuit and buoyancy aid included, ages 6 and up. Prefer it calmer? There's paddleboard, kayak and pedalo hire, and a land-based Puddle Park for ages 2–7.
Allow a couple of hours≈£25 an hour · wetsuit includedBook ahead — sessions sell out · swimmers must manage 25m unaided
Swim and surf beneath white limestone cliffs carved into caves, arches and sea stacks — a Blue Flag beach and one of the north coast's best surf spots, with a seasonal outlet hiring boards and wetsuits right on the sand. The waves that make it famous are the reason to respect it: this is a genuine surf beach with real currents, so swim between the RNLI flags — lifeguards are on in July and August only — and check tide times before exploring the caves.
2–4 hours, easily a dayFree, with free parkingPowerful sea — swim between the flags, lifeguards July & Aug
Cushendun, Co. Antrim · Free · Free village car parks
The Glens of Antrim answer to a hot afternoon: a small, sheltered sandy beach where the Glendun river meets the sea, with a Cornish-style National Trust village behind it and the famous red caves a short walk along the shore. On a calm day the shallows are made for a long, lazy paddle. There's no lifeguard here — it's an unpatrolled beach, so mind the tide and any currents, keep the kids close, and finish with tea in the village.
An easy 1–2 hoursTea room & pub in the villageNo lifeguard — calm days only, mind the tide
Helen's Bay, Co. Down · Free to enter · Pay-and-display parking
The city escape. Fifteen minutes from Belfast, this free coastal country park hides two proper sandy beaches — Helen's Bay and Swinley Bay, popular for paddling and a dip in summer — with grassy picnic slopes above the sand and views right across Belfast Lough. The trick on a scorcher: swim first, then retreat into the wooded glen, where the trees and the waterfall keep things beautifully cool. A café at the visitor centre rounds it off.
Half a day, easily a full oneFree to enter · parking chargeSeasonal dog rules on the beaches & café hours vary — check the day
Tyrella, Co. Down · Free beach · Parking charge in season
County Down's classic: two kilometres of open golden Blue Flag sand with the Mourne Mountains sweeping down to the sea across Dundrum Bay — one of the best swim backdrops in Ireland. The sand is long, flat and made for the run-and-plunge, with grassy dunes behind and an inclusive-beach set-up with accessible equipment. RNLI lifeguards patrol in the main season — swim between the flags when they're on duty, and mind the tide on this open bay at other times.
2–3 hours, easily a dayFree beach · seasonal parking chargeLifeguards main season only — swim between the flags
Ballycastle, Co. Antrim · Free · Town car parks nearby
The swim-then-ice-cream one. A long sandy town beach with a proper promenade, Rathlin Island and Fair Head filling the horizon, and the whole of Ballycastle — cafés, chip shops, ice cream — two minutes from the water. Swim, dry off on the prom, walk into town for a poke, come back for round two. RNLI lifeguards patrol in July and August, roughly 10am–6pm — swim between the flags, and mind the tide outside those months.
2–3 hours, or a full dayTown cafés & ice cream minutes awayLifeguards July & Aug only — swim between the flags
The big splash: a booked morning session at Let's Go Hydro, then out to Crawfordsburn for a picnic on the grass, a paddle at Helen's Bay and the cool of the glen.
The north coast classic: a morning swim between the flags at Portstewart Strand, Whiterocks after lunch for the surf, then ice cream on the prom at Ballycastle.
The Down day: Cranfield's warm shallows in the morning while the lifeguards are on, then round the coast to Tyrella for an afternoon swim under the Mournes.
Keep exploring
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