It's after 'elevated bacteria' was found in the water there.
Claremont Beach is a popular bathing spot all-year round, not far from Howth Harbour.
It's one of 10 or more swimming destinations under the watchful eye of Fingal County Council.
But yesterday, a warning was issued due to "elevated bacteria" in the water there.
The EPA carried out tests and has subsequently issued a "Do Not Swim" notice.
Another sample is due to be taken before the end of the week.
It's believed a high volume of animals and birds contributed to the sample results.
