LEWES, Del. (AP) — This summer, an unexpected surprise greeted more beachgoers as jellyfish populations surged along the Delaware coast, momentarily disrupting the summer enjoyment.

Patrol captains at the beach noted a striking rise in jellyfish occurrences and stings in July, the highest they recall in recent years. Lewes Beach experienced a fourfold increase in stings compared to 2024.

Delaware’s summer waters are home to various jellyfish species, including lion’s manes with tentacles up to 100 feet (30 meters) long, sea nettles, and moon jellyfish.

Jellyfish blooms have become common from Maine to Florida in recent years. Warming waters can create ideal conditions for jellyfish growth.

Typically, Delaware’s five state parks might deal with only a few jellyfish stings over the course of a summer, according to Bailey Noel, a beach patrol captain. However, Fenwick Island State Park recently documented 92 stings on just one day in July. Additionally, three lifeguards needed urgent care after swimming amid jellyfish, Noel stated.

The jellyfish at Delaware’s Towers Beach took Christina Jones, a Philadelphia resident, by surprise. Her two daughters, after getting stung, refused to re-enter the water, she shared.

“The jellyfish are pretty bad,” Jones said. “And not only are they a lot in number, but they’re pretty big.”

Delaware State Beach Patrol started tracking jellyfish stings this year due to the rise in cases, said Noel. Most patrol teams do not track the data.

Lewes Beach Patrol looked after 295 stings in 2024, the inaugural year of data collection, but has already reported over 1,200 cases in 2025, according to Capt. Strohm Edwards. Lifeguards began carrying vinegar solutions, which can neutralize the venom, to alleviate the pain, he mentioned.

But vinegar solutions may cause microscopic venom-coated barbs known as nematocysts to discharge, according to some research. Those experts recommend a baking soda slurry.

While venomous, stings from Delaware’s lion’s manes and sea nettles typically only cause minor irritation and pain, said Edwards. In cases of severe allergic reactions and symptoms — nausea, vomiting and trouble breathing — lifeguards can help.

Jellyfish blooms, sudden fluctuations in jellyfish populations, are not uncommon, said Gisele Muller-Parker, a retired marine biologist who would count dozens of lion’s mane jellyfish during her daily Lewes Beach walks in July. Temperature, salinity and food availability influence jellyfish breeding, and in favorable conditions, such as warmer waters, populations can explode.

“This year, we’ve never seen anything like this,” Muller-Parker said.

The jellyfish were near the end of their life cycle, finishing their reproductive phase and laying their eggs. Those jellyfish will die once water temperatures cool, said Keith Bayha, a research collaborator with the Smithsonian Institution National Museum of Natural History.

The jellyfish boom can harm ecosystems and marine industries, said Bayha, who has studied the animals for more than 20 years and helped identify a nettle species. Fish larvae primarily feed on plankton, but jellyfish can eat both the plankton and the fish. And with few natural predators, the jellyfish food chain is an ecological dead end, said Bayha.

Delaware’s boom this summer is far from alone. Florida’s Volusia County reported hundreds of stings around Memorial Day weekend. Gloucester, Massachusetts, reminded beachgoers to stay safe around jellyfish in mid-July. And in June, Maine’s Ogunquit Fire Department warned beachgoers about the increase in jellyfish after stings were reported.

Jellyfish research is limited, but Muller-Parker hopes more work will be done to assess the ecological ramifications of jellyfish blooms and improve safety advisories.

For now, some unlucky beachgoers will have to rely on home remedies and, in the case of Massachusetts resident Kathy Malloy-Harder’s third-grade nephew, a little bravery.

“When he got stung, he jumped up and started crying and said, ’I’m never coming back to the beach again ever,’” said Malloy-Harder, who had to try two stores to find vinegar for him. But she said that after talking about it “and once the sting subsided, he was interested in coming back and enjoying the beach.”

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Whittle reported from Portland, Maine.