Alertness to Hazards Makes Beach Vacation Fun : How to avoid stinging jellyfish, sea urchins, stingrays--and what to do if you don’t.

Vacations in and around the ocean can relax and rejuvenate, whether travelers walk on the beach, surf or dive. But ocean visits can quickly turn disastrous if vacationers end up on the cranky side of a sea urchin, stingray or other sea creature.

Knowing how and where to step in the surf, what first-aid supplies to carry and when to seek professional help can minimize the dangers, according to marine hazard experts.

Many encounters with ocean creatures are minor and require simple first aid, said Dr. Paul Auerbach, professor of surgery at Stanford University Medical Center and author of “A Medical Guide to Hazardous Marine Life” (Mosby-Year Book, Inc.).

Yet there are exceptions, such as the potentially lethal box jellyfish which, with a significant sting, can cause fatal heart and lung failure, Auerbach said. “It is uncommon, but there are deaths every year,” he said. Immediate medical attention is vital.

The box jellyfish commonly inhabits the coastal waters of Northern Australia from October to May, where a vigorous education campaign--including posted signs--alerts swimmers and divers to the potential danger on the beach.

Even jellyfish that wash ashore should be avoided, said Wayne Pawelek, diving safety officer for Scripps Institution of Oceanography in La Jolla. “A dehydrated tentacle can stay active for days.” He particularly warns parents to watch small children, who have been known to “pick up tentacles and pop them into their mouths.”

Visitors to South Florida and the Caribbean--especially in April through July--should be wary of “seabather’s eruption,” a skin rash caused by what some people mistakenly refer to as “sea lice.” A fever sometimes accompanies the itching and rash, which may resemble tiny insect bites in areas covered by a bathing suit or T-shirt. There is speculation that it is caused when the almost-microscopic larvae of “thimble” jellyfish become trapped as water flows through the clothing, according to research published in the Journal of the American Medical Assn.

“Rinse off thoroughly and change suits,” Auerbach advises. “Discard the bathing suit.” Those who contract these “sea lice” and then wear the contaminated swimsuit again, may experience a recurrence, Auerbach said. The condition usually resolves itself, but some people require treatment with antihistamines, topical steroids or other medicine.

In California, beach-goers from the Central Coast to Mexico are most likely to be bothered by stingrays and sea urchins, said Pawelek. “Stingrays love the shallow water and will nestle down in the sand,” he said. Sea urchins prefer rocky areas.

Treat stingray and sea urchin stings by immersing the affected area in 110- to 113-degree water for 30 to 90 minutes, Auerbach said.

“That usually takes a lot of the pain away,” Pawelek added. “But it is similar to a bee sting. Everyone reacts differently.” He recommends medical attention.

Sea urchins, purplish and about the size of a golf or tennis ball, can leave their spines in the skin. Unless these are completely removed, Pawelek said, they will work their way deeper.

The way you walk in the ocean can protect you from bites and stings. “Shuffle your feet, don’t pick them up,” Pawelek said. “If you step on top of a stingray, its tail comes up and around and stings you.” By shuffling, it is possible to frighten the stingray away before you get close enough to be stung, he said.

Reef or beach shoes, sold at sporting goods stores, are a good idea, Auerbach said. “They should have a fairly thick sole to prevent rupture,” he said. “Or wear (sea) booties with very thick rubber soles.”

Deciding when to seek medical attention can be complicated, but Auerbach offered some general guidelines: Seek help if someone has difficulty breathing, if their lips or tongue are swelling or if they collapse. Anyone who acts confused or otherwise unusual needs professional attention, he said, as do people with intolerable pain or uncontrolled bleeding after an ocean accident.

Taking along emergency supplies can minimize disaster. Make your own topical decontaminant, Auerbach suggested, by mixing equal amounts of household vinegar and rubbing alcohol in a plastic bottle.

Despite the hazards, Auerbach and Pawelek insist that the ocean is safe if travelers are careful. “If you know what you’re doing, any place is safe,” said Auerbach, who is a veteran diver, “if you can just resist the urge to touch things.”