Maybe you are familiar with the dreadful feelings that accompany an itchy, red rash that corresponds with the outline of your wetsuit or shortie. Maybe you’ve heard horror stories about the worst rash your dive buddy ever had, and you’re hoping to steer clear of problems. Either way, Sea Bather’s Eruption and Seaweed Dermatitis are two fairly common skin problems associated with our favorite sport – and they’re easily confused. Here, we’ll compare the two skin maladies and provide insight into preventing and treating them.
Sea Bather’s Eruption
Sea Bather’s Eruption is a form of itchy dermatitis. It is caused by a hypersensitive reaction to thimble jellyfish in their larval stage, along with sea anemone nematocysts and other larval cnidarians. If you’ve ever heard the term “sea lice,” this is the same condition. Very much like an allergic reaction, it occurs mainly in tropical waters and in Florida, as well as in other areas washed by the Gulf Stream, including Bermuda, the Bahamas, the Philippines, Brazil, and Thailand. As global weather patterns are changing, these larval cnidarians may be present in areas which were previously free from problems associated with them.
Symptoms don’t typically arise until after you have taken a shower or dried yourself in the sun after diving. The first thing you’ll notice is severe itching with red bumps as large as 1.5 centimeters across. These will show up primarily on areas that were covered by hair or water-permeable clothing during your dive, or even during a swim in ocean water. The reason for this is that these sticky-bodied, microscopic organisms can become trapped inside gaps between the skin, hair, and clothing. Once you leave the ocean, the little cnidarians die and discharge their nematocysts once you’ve exposed them to fresh air or fresh water.
To prevent Sea Bather’s Eruption, remove gear and clothing rapidly after leaving the water, and rinse off thoroughly with sea water before your skin dries. Try not to rub too much, since crushing the cnidarians causes them to discharge their nematocysts and will give you a rash. Get a hot, soapy shower as soon as possible, and don’t forget to launder clothing and clean gear thoroughly.
Unless you have a severe case, you can treat your rash with topical anti-itch cream containing diphenhydramine and/or hydrocortisone. Wear loose clothing and avoid scratching the area as it will only cause problems to worsen.
Seaweed Dermatitis
Seaweed Dermatitis looks a lot like Sea Bather’s Eruption, which is why the two are often confused for one another. This problem is caused by marine cyanobacteria with tiny threadlike bodies, which are found in fresh and salt water environments throughout the world. It commonly occurs in Hawaii, particularly during the summer when trade winds are at their peak. Toxicity and severity varies by location and by season, and not all strains of seaweed are toxic. In fact, of the more than 3,000 varieties present, scientists have pinpointed a particular species called Lyngbya Majuscula as the culprit. It normally grows in clumps and has a blackish-green to olive hue; it sometimes is yellow, red, or gray. This is just one more reason to avoid touching anything while diving, and another reason why good buoyancy control techniques pay off.
If you are affected, you’ll feel an itching, burning sensation that begins within 24 hours of leaving the water. Other possible symptoms include skin sores, headache, fatigue, irritated nose and throat, and swollen eyes. Luckily, treatment is fairly simple. First, wash thoroughly with soap and water, rinsing your whole body and flushing your eyes in the process. Next, rinse your body with rubbing alcohol and let it dry. Afterward, apply a topical OTC hydrocortisone cream or calamine lotion. Your doctor may recommend antihistamines, and if a subsequent infection occurs, you may need antibiotics.
While neither of these problems tends to be serious, and while neither is contagious, both can take the fun out of a diving vacation. Practicing excellent hygiene and keeping your gear clean can help to prevent you from ever enduring them in the first place.