Stinging bites from snorkeling?

Question

We are heading to Maui in a few weeks. We were there around the same time Oct/Nov last year. I love to snorkel from shore and usually wear a long sleeve rash guard or wet suit over my top half, but nothing covering my legs. Last year, I was snorkeling at the south end of Wailea Beach and the water was kind of cloudy in areas and later I had three larger-than-pea-sized itchy red splotchy marks on my calves. Another day we were snorkeling at a different beach in West Maui and I later noticed about 10 different looking smaller red bites in a V shape on my calf, but I'm not certain if those came from the water, or possibly I was bit by something on the beach (no see ums? or maybe even bedbugs?). All of these bites were were red and itchy for several days. Definitely not mosquito bites. A google search suggested it could have been "sea lice" (jellyfish larvae) or "stinging seaweed." I never hear of other people experiencing this in Maui, and DH was unaffected. There is a product on the market called "Safe Sea" sunscreen that is supposed to protect against sea lice and jellyfish, but I'm not even sure that was what was stinging me. Has anyone else experienced this?

Answer

Experiencing stinging bites or rashes after snorkeling in Maui is not uncommon, though it doesn’t happen to everyone. Based on your description, there are a few likely culprits for the red, itchy marks on your calves:

Possible Causes

Sea lice (jellyfish larvae): Sea lice are tiny jellyfish larvae that can sting and cause small red, itchy welts, usually in clusters or streaks. They are most common during certain months, particularly when water temperatures are warmer and plankton is abundant. They can cause reactions even when just brushing against a swimmer's skin.
Stinging or bristle seaweed: Certain types of marine algae or seaweed can have fine hairs or cells that cause skin irritation. Contact can produce red, itchy splotches similar to what you described.
Other marine organisms: Small jellyfish, anemones, or coral can cause stings or skin irritation, often leaving marks that resemble tiny bites or rashes.
Sandflies / no-see-ums: Though typically affecting both people in the same area, sandflies can bite exposed legs on the beach before or after snorkeling. Reactions can vary by person, which might explain why your husband was unaffected.

Prevention Tips

Wear a full-body rash guard or thin wetsuit that covers the arms and legs to reduce exposure to sea lice or stinging organisms.
Rinse off in fresh water immediately after snorkeling to wash away any irritants.
Consider using protective products like Safe Sea or similar sunscreens designed to provide a barrier against jellyfish and sea lice. Test these at home before travel to ensure compatibility with your skin.
Avoid swimming in areas with noticeable blooms of algae or jellyfish, and check local beach advisories if available.

Treatment for Stings / Irritation

Rinse the affected area with vinegar or saltwater (not freshwater) to neutralize any lingering stingers, especially if jellyfish larvae are suspected.
Apply over-the-counter hydrocortisone cream or antihistamine creams to relieve itching.
Oral antihistamines can also help with inflammation and itching.
Keep the skin clean and avoid scratching to prevent secondary infections.

While these reactions are typically mild and resolve within a few days, if you experience severe swelling, blistering, or systemic symptoms (fever, difficulty breathing), seek medical attention immediately.

In summary, what you experienced is likely sea lice or stinging marine organisms, and the fact that your husband was unaffected could be due to differences in exposure, skin sensitivity, or the areas of your body that were exposed. Protective clothing, immediate rinsing, and barrier products are your best defense when snorkeling in Maui.

Stinging bites from snorkeling?

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