The RNLI is urging people taking part in open water swimming to be aware of the risks, after four people were rescued in Sligo last winter.
The four swimmers in Sligo found themselves in trouble in large swells.
One person was recovered by the RNLI, one made is ashore on their own, and two others were airlifted to safety by the Coast Guard helicopter.
The RNLI says there's been a big increase during the Covid pandemic in the number of people taking up open water swimming, which has many benefits, but is warning that people be aware of the risks.
Cold water shock is a very real danger for anyone entering water that's 15 degrees Celsius or below, while hypothermia can also pose a risk - especially at this time of year when the average sea temperature around Ireland is just 6-10 degrees.
With the sea temperatures still dropping and reaching their coldest around March, the RNLI says the effects of cold water, combined with weather conditions and any personal health issues should be taken seriously before venturing in.
They're advising that people should not swim alone, should wear a wetsuit and bright swim cap to make yourself visible to others, and should stay in your depth and swim parallel to the shore.