Sea Swimming in Ireland: Tides and Currents

Check the forecast and tide times before every sea swim, choose a lifeguarded beach and swim between the red and yellow flags where possible, and know what to do if a rip current takes you: do not fight it, swim parallel to the shore or float, raise a hand and shout. If you see someone in difficulty, call 999 or 112 and ask for the Coast Guard.

Why tides matter

Tides are the regular rise and fall of the sea, roughly twice a day on Irish coasts. They change the depth of a swimming spot, how far the water is from the car park, and the strength and direction of currents. A beach that is calm at high tide can have a strong flow over a sandbar at the turn of the tide, and a slipway that is easy to enter at high water can become slippery rock at low water.

The Irish Coast Guard and RNLI advise walkers to check the tide times to avoid being cut off by a rising tide, and to check tidal conditions before swimming or going afloat. A multi-agency appeal from the same bodies recommends checking the weather forecast, including tides, before heading out. The HSE's water safety advice for families points to Beaches.ie for conditions and tide times, and notes that Water Safety Ireland publishes a list of beaches and waterways with lifeguards on duty in summer.

A pre-swim tide check

• Look up high and low water times for your exact spot, not just the nearest big port. Local timings can differ.
• Decide your entry and exit points for the state of the tide, and check you can get out at both ends of your plan.
• Ask local swimmers or lifeguards about known currents at your spot. Local knowledge is often better than any app.
• Know spring and neap tides. Spring tides come around new and full moon and have the biggest range of the month, with higher highs, lower lows and usually stronger water movement. Neap tides come at the quarter moons and have the smallest range and weaker flow. Confirm the dates and times for your spot in a tide table.
• Avoid river mouths, estuaries, piers and groynes unless you are with someone who knows them, since flows there can be fast.
• Check the wind. Offshore winds make it easier to be blown out and harder to return.

Headlands, wind against tide and forecasts

Tidal streams speed up around headlands and between islands and the shore, so a calm bay can sit next to fast, disorderly water just round the point. When the wind blows against the direction the tide is flowing, the sea becomes shorter, steeper and more broken, especially at headlands, harbour mouths and over banks. Plan swims inside the bay, away from the point, and check the wind direction against the tide.

For forecasts, Met Éireann publishes marine forecasts, including a Sea Area Forecast for Irish coastal waters out to 30 nautical miles and gale warnings, on met.ie. Check also for any inshore waters forecast it publishes for your stretch of coast. For tide times, the Marine Institute offers tide predictions for Irish coastal locations (they show water level only and leave out storm surge from wind and pressure), and harbour authorities such as Dublin Port publish local tables. Compare a second source for your exact spot. See also storms, swell and big tides for swimmers.

Flags, harbours and piers

Red and yellow flags mark the lifeguarded area. A red flag means danger, and nobody should go in. A black and white chequered flag marks a zone for surfboards, paddleboards and kayaks, which swimmers should avoid. An orange windsock warns of offshore or strong winds, and inflatables should not be used (RNLI flag guidance). Harbours, piers and slipways have no flags, and they add hazards such as boat movements, fast flow around pier ends and slippery steps, so ask local swimmers before using them.

Rip currents: what they are and how to spot them

A government press release issued with the Irish Coast Guard, RNLI and Water Safety Ireland describes rip currents as strong, outward-flowing currents that can carry swimmers out to deeper water. They tend to flow at 1 to 2 mph but can reach 4 to 5 mph, which is faster than most people can swim. They are sometimes identified by a channel of churning, choppy water on the surface, and they also form near river mouths, estuaries and structures such as piers and groynes. RLSS UK adds that rips often run through channels or gaps between sandbars, where the line of breaking waves looks interrupted and the water can look deceptively calm. Offshore winds make rips more dangerous.

They can be hard to spot, particularly for beginners. That is why the standard advice is to swim at lifeguarded beaches between the flags, where lifeguards place the flags in the safer area.

If a current takes you

The advice from the gov.ie release is: do not try to swim against the current or you will exhaust yourself. If you can stand, wade rather than swim. If you can, swim parallel to the shore until you are out of the rip, then head to land. Raise your hand and shout for help. The multi-agency appeal adds that if you are still in difficulty you should float on your back like a starfish and call for help.

In cold water the first minute is the hardest. The cold water shock response makes breathing fast and uncontrolled, and panic makes it worse. The RNLI's float-to-live advice, covered in cold water shock and float to live, is to let the shock pass before you try to do anything else.

Cold water and currents together

Strong currents and cold water combine badly. Swim failure, where cooled muscles stop working, can leave a swimmer unable to make progress against even a modest flow. Keep swims short and close to the shore in cold conditions, stay within your depth, and swim parallel to the beach rather than straight out. Winter swimmers should treat a calm-looking sea with respect, particularly around estuaries. See winter sea temperatures in Ireland by month for how cold the water gets.

Building local knowledge

The safest swim spots are the ones you know. Swim with an established group where possible, learn how the beach changes over the tide, and watch lifeguards' flags. See open water swimming groups and safe spots in Ireland and sea swimming in Ireland for beginners.