Portuguese Man o’ Wars on the Atlantic Coast: Warning for Beachgoers in Southwestern France

Arcachon – 05.08.2026: Portuguese man o’ wars have reappeared on beaches in southwestern France. According to reports by Franceinfo, the colonial marine animals were observed from the Arcachon Basin to the Basque coast. Due to the danger posed by their long tentacles, some beaches had to be temporarily closed to beachgoers. The animals are often mistaken for jellyfish because of their bluish floating bodies.

Portuguese man o’ wars are not individual jellyfish, but colonies of specialized organisms. They drift on the water’s surface with a gas-filled floating body that usually shimmers blue to violet. Long tentacles hang beneath it. Even animals that have washed ashore or appear to be dead remain dangerous because the stinging cells in their tentacles can still react.

According to health authorities, contact can cause intense burning pain, reddish welts and skin injuries. In rare cases, symptoms such as dizziness, nausea, breathing problems or an allergic reaction may also occur. Children and people with pre-existing conditions should seek medical examination particularly quickly if they experience such symptoms. Anyone who notices circulatory or breathing problems after contact should call emergency services on 112 immediately.

Health authorities advise carefully rinsing the affected area with seawater first. Fresh water can activate remaining stinging cells and intensify the reaction. Vinegar, ammonia and rubbing with sand are also unsuitable. Visible tentacle remains should not be removed with bare hands; gloves, a card or tweezers are better options, provided this can be done without further contact.

After rinsing, heat can relieve pain: the affected part of the body should, if tolerated, be treated with warm water for around 20 minutes. The temperature must not cause burns. Medical assessment is then advisable, especially in cases of extensive injuries, persistent pain or symptoms beyond the skin. Beach supervisors and rescue services can assess the current situation on site.

Holidaymakers should therefore observe the following: do not touch or remove blue, balloon-like objects on the beach or in shallow water, and keep children away from them. Notices issued by local authorities, flags on supervised beaches and instructions from rescue services must be followed. The City of Arcachon deploys lifeguards during the summer season; their information may vary depending on the beach and the conditions on a given day.

The latest sightings come during the peak season on the Atlantic coast, when many beaches between Gironde, Landes and Pyrenees-Atlantiques are heavily visited. Portuguese man o’ wars are carried by wind and ocean currents, which means their distribution can change at short notice. Clear water at one beach is therefore no guarantee that no animals or tentacles have washed ashore on nearby stretches of coast.