Waterford beach off limits due to influx of venomous Men-of-War

Sarah Slater

Bathers are being advised to avoid the water off the Co Waterford coast due to an influx of the venomous Men-of-War.

The Portuguese Man-of-War is often called a jellyfish, but is actually a species of siphonophore, a group of animals that are closely related to jellyfish.

They were sighted off the popular area of Ardmore Beach by lifeguards on duty on Sunday afternoon.

Waterford City and County Council said they have placed a red flag along the beach and “member of the public are advised to avoid the water”.

Men-of-War are recognisable by their bright blue, gas-filled "sail" and long tentacles.

Found mostly in tropical and subtropical seas, Men-of-War can be brought to further afield by winds and ocean currents and sometimes float in legions of 1,000 or more, according to the US National Ocean Service.

They can grow to an average of 10 metres and may extend by as much as 30 metres. The tentacles contain stinging microscopic capsules that deliver venom capable of paralysing and killing small fish and crustaceans.

While their sting is rarely deadly to people, it packs a painful punch and causes welts on exposed skin and may still sting you even weeks after having washed ashore.

In 2025 and 2026, a rise in water temperatures and strong Atlantic winds led to an increase in sightings along the Irish coast.