Swim Ireland has issued safety alerts on all its social media channels amid calls for open water swimmers to keep safe this weekend.
It follows unprecedented pressure on emergency services, after a surge in popularity for the sport.
The challenges involved with open water swimming greatly intensify at this time of year, with falling water temperatures, fading light, stormy weather and stronger tidal conditions.
You can find reliable weather forecasts and warnings via @MetEireann
There is tidal information here: https://t.co/73eivMdoB4
And at every swimming spot there are local, seasoned swimmers, who would love to help you.
— Swim Ireland (@swimireland) November 20, 2020
Cold water shock is a threat, as well as fatigue, with swimmers tiring more quickly than they might expect during the winter months as their bodies expend extra energy to keep warm.
Peter Conway, chairman of Swim Ireland, said there had been a massive increase in the number of people taking to open water following the closure of indoor facilities due to Covid-19 restrictions.
He said: “As air temperatures drop, as water temperatures drop, as the weather becomes more unpredictable, safety comes to fore.”
A Water Safety Ireland video went viral in Ireland overnight with hundreds of thousands of views.
Deputy chief executive Roger Sweeney said it indicated the huge level of interest around the country.
“There has been a phenomenal surge in the number of people taking to sea swimming at the moment,” he said.
“We all know season swimmers who are year-round and are very experienced at that and are usually very safe.
“However, right now, we're seeing tens of thousands of people who would normally be swimming in pools without access.
“When they don't have access there's a percentage of those who are getting into the sea.”
The Irish Coast Guard and the RNLI on Friday issued an appeal for the public to get up to speed on safety before taking to the water – but stressed they still want people to ring 112 without hesitation if they spot someone in difficulty.