10/01/2025
Seabather's Eruption: Rash Affecting Auckland Beachgoers
Auckland Council Urges Caution as Rash Plagues Beachgoers
Auckland Council is advising beachgoers to take precautions after swimmers have reported experiencing itching, rashes, and red spots following water activities.
Darryl Thompson, the council's environmental health technical specialist, identified the condition as seabather's eruption. This rash is caused by stings from the nematocysts, or stinging cells, of certain sea anemones and thimble jellyfish.
However, Dr. Dennis Gordon, emeritus researcher at the National Institute of Water and Atmospheric Research (NIWA), suggests the rash could be the result of sea lice, a different type of organism altogether.
Gordon believes the rash in Auckland is more likely caused by siphonophores, marine creatures that resemble long, stringy forms with small bubbles attached to them, found in plankton.
"Divers call them 'long, stringy, stingy things,'" said Gordon. "These little bubbles are individual organisms in a colony, which can detach and become trapped between your swimsuit and skin. The movement of your swimwear activates these creatures, causing irritation."
On Tuesday afternoon, Auckland resident Tracy and her two daughters developed a rash after swimming at Takapuna Beach. Tracy shared her experience with RNZ, noting her daughter had spotted a jellyfish during the swim.
As of Wednesday, Safeswim had only issued cautionary warnings for Ōrewa Beach and Milford Beach, but on Thursday, additional alerts were added for Takapuna Beach and Big Manly Beach.
Juliette, another Auckland mother, initially thought her daughter had chickenpox after swimming at Ōrewa Beach on Monday. "It was only when I saw Tracy's post on Facebook that I realized what it was," she said. "My daughter developed pimples in areas where her swimsuit had been."
Laura, who swam at Mairangi Bay Beach on Wednesday, shared that a pharmacist identified the rash as sea lice bites. "Our daughter had red spots all over her torso, arms, and legs. The pharmacist mentioned that several others had come in with the same symptoms."
Sea lice tend to bite exposed skin, leaving red, itchy spots similar to flea or mosquito bites. In contrast, seabather's eruption typically affects areas covered by swimwear, causing hundreds or thousands of small red dots that may merge into larger patches or weals.
The Auckland Regional Public Health Service reports that children are most affected by seabather's eruption. The rash can range from mild to severe, often lasting a week or more.
To alleviate symptoms, the service recommends calamine lotion, antihistamines, or mild steroid creams. However, in some cases, particularly with children, symptoms can worsen, leading to headaches, nausea, and fatigue. These cases may require treatment with steroid tablets or syrup.