Swim With Caution: Summer's Beach Dangers

During the summer, it's easy to get caught up in the sun, surf and sand at the beach. Slather on some sunscreen and you're ready to go, right?

Not so fast.

Dangers lurk beneath the surf that can put a damper on any summer holiday.

Marine animals, including jellyfish, Portuguese man-of-war and lionfish — or worse, tiger sharks in some areas — can make things painful for unwitting swimmers.

By staying informed and being aware of potential beach dangers, beach visitors can avoid discomfort, injury or even a trip to the emergency room.

In the summer, the probability of run-ins with marine animals — dangerous or otherwise — is much higher. Swimmers are catching waves and sea creatures move toward the coast in search of warmer waters, said Christopher G. Lowe, professor of marine biology at California State University, Long Beach.

While marine animals themselves can cause some hazardous situations, some of the most dangerous beach encounters are initiated humans who flock there during the summer, Lowe said.

Beachgoers should consider that the central cause of most beach dangers is human behavior, not animal behavior, he added.

"Encounters are going to be much higher in the summer than in the spring, fall or winter when most people are in the water," Lowe said. "Remember, we're guests in the ocean — it's a wild environment and there's more than just one of us taking advantage of those habitats at the same time."

He added, "If it's a matter of reservations, were always crashers to the party. We crash the party and in summertime we crash the party in huge, huge numbers.

Basic suggestions from the experts included being well informed about beach areas and marine wildlife.

"People need to read up on the areas they're going to," Lowe said. "They need to be aware of their surroundings. There are not safety regulations or rules that the animals have to follow. Weird things do happen."

Here are some important facts, warnings and suggestions to consider before you dive in.

Tiger Shark

Keep away from river mouths and sandbars to avoid tiger sharks and other predatory fish.

Where are they? When can they be found?

In some locations such as Hawaii and parts of the Gulf of Mexico, tiger sharks are spotted year round.

They often are encountered by swimmers in murky water, near sites where rivers feed into an ocean area or near runoff areas.

Beachgoers should avoid swimming at dusk and dawn, said Andy Dehart, general manager at the National Aquarium in Washington, D.C.

Swimmers should stay away from baitfish like minnows, he said, because the small fish tend to attract larger, predatory fish.

"If there's a sandbar present — bait fish will hang out inshore or closer to the beach," he said.

Because the sharks do see in color — high contrast colors like yellows, whites or silver — they spot and follow the shiny bait fish. Humans have to be particularly careful when they're swimming or wading in those areas.

The danger

"The worst case scenario is that you get bit. Tiger sharks can get up to 14 feet or so and a little nibble from a tiger shark can do a lot of damage," Lowe said.

But it is very seldom that flesh is removed, and it is even less likely that people are consumed by sharks, Lowe said.

"It's not that they are attacking people because they consider them food — when you get big, you can bite first and decide whether you like it later."

How big is the threat?

Of the 71 near-shore shark attacks worldwide last year, only one was fatal, the National Aquarium's Dehart said.

"Remember that you have a much bigger chance of being mauled by the neighborhood pit bull than you would by a tiger shark," Lowe said.

"The good thing is if you see a shark, you should consider yourself lucky because about 85 percent of people who are bitten by sharks never see the shark coming."

What to do If you see the animal, the best thing to do is get out of the water as carefully and calmly as you can and then you will "have some great stories to tell," Lowe said.


Stingrays are particularly dangerous near warm, coastal waters where they'll hide from predators under the sand.

Where can they be found?

Stingrays can be found up and down the East Coast and on West Coast shores, Dehart said.

Lowe said most stingrays that aren't caught by fishermen during the middle of the summer typically move to warmer, calmer waters to forage for food or rest. The finer sand in those shore areas provides protection from predators.

"A lot of stingrays to avoid predators bury themselves in the sand," Lowe said. "Most encounters with stingrays result in someone stepping on them. Their interactions with people are negative because most encounters with stingrays result in someone stepping on them."

When can they be found?

Beachgoers should be most cautious when coastal waters are the warmest in late summer or early fall.

During that time, the stingrays are going to be in waters where people are most likely to be out surfing, wading or playing.

The danger

Stingrays have a poisonous barb on their tail that contains a mucus with a toxin. When the barb punctures skin, cells in the toxin rupture and the toxin oozes into the wound. The pain of a stingray wound — swelling and stinging — is usually localized unless a person has an allergic reaction to it.

An infection can after the laceration. In addition, a piece of the barb can break off in one's leg or arm and can get infected, Dehart said.

What to do

"The best thing you can do is put part of the body that was stung in water as hot as you can stand — 104 to 105 degrees — the heat denatures the toxin," Dehart said.

However, if you have an open wound that you have to clean out, intense pain and swelling can follow that might necessitate a trip to the emergency room, Lowe said.

The best way to avoid stingray injuries is doing the "stingray shuffle."

"The stingrays bury in the sand just below the surface. If you shuffle your feet and you nudge them with your feet, they'll skitter away because you're not pinning them down," he said.

Also, some species are more "skittish" than others, Lowe said. While some species will scatter if they sense vibrations within 10 feet, others will avoid predators by remaining perfectly still buried in the sand — and those are the ones to watch.

Find out more

Round stingrays are the "number one" culprit in beach attacks, Lowe said. They get to be as big around as a dinner plate and their poisonous spines only grow to about two inches long.

Lowe said marine biologists have had the opportunity to study round stingrays closely.

"We know a lot more about behavior and lifeguards are using that behavior to better educate the public about what's in the water there and a little demonstration how to do the stingray shuffle," he said.


These "pet fish" have established a population in coastal waters along the southeast.

What are they?

Lionfish are reef dwellers and can typically be found around coral or rocky reefs. The fish have spines that, if stepped on, will release a poison.

Where can they be found?

According to Dehart, lionfish are venomous species that "don't shy away from people but are not aggressive."

"If you see one, don't investigate too closely. They will put up their spines and they can sting," he said.

Lionfish are "fish tank" pet fish that are traditionally found in tropical Indo-Pacific waters.

Of the more than 20 species in Florida that have been found off reefs, the only type of pet fish that is successfully bred and established is lionfish, Dehart said.

As an invasive species, lionfish populations have flourished in the Southeast and, as a result, their populations are exploding. They have been spotted "as far up as some of the Carolinas," Lowe said.

When can they be found?

Summer near shorelines where the water is warmer.

The danger

The poison gets into the wound, causes intense pain, swelling and in some cases allergic reaction.

Fishermen might catch them they have to be careful when they handle them, Lowe said, because the fish "have a good defense mechanism and they know it."

How big is the threat?

Lowe said the fish are more of a threat for fisherman than they are for most beachgoers, even though swimmers do have to be careful in reef areas.

Find out more

Be aware that lionfish are becoming more prevalent. While it used to be an oddity to see the fish out on a reef, Lowe said, their populations are growing and negative encounters with the creature are becoming more common.

Beach travelers should check online — many coastal states now have warnings when lionfish are sighted.


Jellyfish are the cause of many a sting at the beach.

Where and when can they be found?

Jellyfish can be found year round in large populations across the coastal United States.

Depending on what coast, what time of year, depending on the lunar phase, local sea conditions and water temperatures. For example, box jellies tend to swarm during certain lunar phases and scientists can now predict those swarms.

The danger

Jellyfish have poisonous stinging cells that can also cause intense pain and swelling, can be hard to see because they are gelatinous and have reasonably short tentacles.

In most cases, a swimmer has to make direct contact with the jellyfish to be stung because the fish's stinging cells are pressure sensitive.

"That fires a little harpoon dart form the cell into your skin and that toxin is pumped in," Lowe said. "When people get a tentacle on them the best thing to do is gently pull it off, not smush it in."

Depending on the species, the injury can range from severe burning to a burnlike wound to a raised welt.

"People do have allergic reactions to them, and they can kill you if you're not careful," Lowe said.

The cure

Lowe suggested an unlikely cure for jellyfish stings: white vinegar.

"A squirt bottle with some vinegar — that breaks down the toxin so that it relieves the pain and swelling," he said.

Another useful treatment for jellyfish stings is hot water.

"Water-based toxins are temperature sensitive so if you heat them up they break down and lose their toxin effect," Lowe said.

Dehart suggested that swimmers use ammonia to wash the stinging cells away and that freshwater will make the sting hurt more.

Find out more

Local towns or counties have good information online about dangerous marine animals. Lifeguards are usually well-informed about beach dangers.

Portuguese Man-of-War

This colony of organisms develops long tentacles that can be a hazard for swimmers and other beachgoers.

What are they?

Man-of-War is a close relative to a jellyfish: It's a colony of animals, and different individuals within the colony have different jobs, Lowe said.

When can they be found?

Dehart said the Portuguese Man-of-War can be encountered toward the end of the summer.

The animals' tentacles can get to be 165 feet long and are a hazard for swimmers and divers.

Man-of-War can be easily spotted because they move by floating on the surf, but their tentacles can stretch a great distance and can go unseen.

Usually swimmers "don't even know what they're being stung by," Lowe said.

Quite often, people walking down the beach will get stung on the foot because even dead man-of-wars that wash up on the beach can still sting, he said.

The danger

"Some people do have allergic reactions to them. They'll have trouble breathing, a typical severe allergic reaction," Lowe said.

In most cases there will be a stinging, burning feeling where the tentacles make contact with the skin. Hot water can be used to treat the wound.

Around the neck and chest, man-of-war stings can sometimes be fatal and can leave a scar, Dehart said.

How big is the threat?

Portuguese man-of-war can be the number one "dangerous beach organism" in certain areas, mainly because of their large populations.

One of the best ways for beachgoers to protect themselves from stings is to wear rash guards. That can protect swimmers from the sun, as well as from unwanted stings.

"It's a Lycra top or you can even get full suits — pants, shorts and tops. It's good sun protection as well as sting protection," Lowe said.


What are they?

Tiny, microscopic plantlike organisms. The photosynthetic organisms float in water and some species produce toxins.

"When they bloom, you get billions and billions of them in the water and they can ooze poisonous toxins," Lowe said.

Where can they be found?

In most coastal areas.

The danger

Some species of phytoplankton give a stinging sensation or an itchy sensation when swimmers swim through them.

The burning sensation usually goes away pretty quickly; the organisms are so small that burning itchy sensation goes through in a matter of hours. Lowe suggests that beachgoers can take Benadryl to alleviate the symptoms of an allergic reaction.

Scientists are still trying to get a better idea of where and why these phytoplankton populations erupt into sometimes hazardous algal blooms.

Usually it's closer to shore where you have runoff going into the ocean and water temperature has to be just right and conditions have to be just right to induce them.

When they occur in high concentrations, the algal blooms will cause "red tides." Red tide algal blooms can irritate swimmers' eyes and disrupt breathing.

"The water becomes reddish-brown because the density of these organisms is really, really high," Lowe said. "The biggest danger isn't from being stung but from marine organisms eating the blooms and filtering those phytoplankton and toxins through."

Those marine organisms can later be poisonous to the humans who consume them.