Ouch! Don’t Get Stung While Diving


Underwater, you should only have to avoid sharks and animals that bite, right? (See our earlier post for tips on dealing with hazardous marine animals!)

A lot of sea creatures use venom to kill prey and defend themselves. Fortunately for us, humans are not their normal prey — however, it can mean bad news for you if you get up too close and personal with one, either intentionally or more often, accidentally.

(What’s the best defense? A wetsuit or Lycra suit – click to view!)

Envenomation (the process which venom is injected) can occur from simply brushing against an organism, a puncture or from a bite. In this post, we’re going to focus on organisms who deliver venom by contact, since these are the most common things we encounter as divers.

What Causes the Stings?

Members of the phylum Cnidaria, many of these organisms contain cells called nematocysts, or special cells in their tentacles or extremities, which have a barbed thread that delivers a toxin. Contact can trigger millions of nematocysts to pierce the skin and inject venom, which if you’ve ever been stung, you know can hurt!

What Are the Most Common Stinging Contact Sea Creatures?

Corals: Commonly called fire coral, these stings are generally fairly mild. A rash can form and may take days to subside.

Hydroids and Anemones:  Hydroids, which look like feathery plants, and anemones can be very pretty but don’t touch or you may regret it! Reactions are usually similar to coral encounters.

Regular Jellyfish:  Most jellyfish stings are relatively mild, but some can be very painful, causing rash, blisters and swelling. Most jellyfish drift and can be avoided, but their tentacles can hang far from the main body, so if you see any, be prepared to encounter a tentacle.

Portuguese man-of-wars: These look like floating, iridescent balloons and they can pack a wallop of a sting! With tentacles that average 33 feet long, but can reach 165 feet, snorkelers and divers on the surface may get tangled in a tentacle and not even know what got them. You can even be stung from a dead one.

Sea Wasps / Box Jellyfish: These species live in waters off Northern Australia and throughout the Indo-Pacific. Their venom is considered to be among the most deadly in the world, often causing divers to go into shock and drown, or die of heart failure before they reach the surface. Survivors often suffer severe pain for weeks and scarring. These organisms can propel themselves better than regular jellyfish, so if you see one, move away!

What To Do If You’re Stung:

  1. If the unfortunate happens and you do get stung, the first step is to remove any tentacle or other pieces  — avoid rubbing, because rubbing can cause the nematocysts to fire, releasing more of the painful venom! Try to use gloves, or if you must use your fingertips, make sure to wash them thoroughly afterwards.
  2. Most experts recommend neutralizing the toxin using household vinegar if it’s available, or seawater if not. Do not use freshwater – it can cause the nematocysts to fire. Some people believer urine helps, if you can get over the gross factor.
  3. In some instances, such as a Portuguese man-of-war, submerging the affected area in hot water can also neutralize the nematocysts.
  4. Topical and oral antihistamines such as Benadryl can help.
  5. Seek medical attention immediately if you (or whoever is stung) shows any symptoms such as trouble breathing or loses consciousness. Severe stings can cause vomiting, fever, chills, muscle cramps and abdominal pain. For some individuals, especially anyone with pre-existing cardiovascular or respiratory disorders, the reaction can be even more serious, resulting in death.

The above are general recommendations. If you plan to dive in areas where you’re likely to encounter a venomous organism, do a little research on treatment and make sure you bring along the necessary treatment items such as vinegar (a spray bottle works best). DiversAlertNetwork (DAN) is a reliable source of information.

The Best Treatment for Cnidarian Stings is Prevention!

  • Like things in the ocean that bite, it’s best to leave the organism (dead or alive) and it’s dwelling alone (look but don’t touch!).
  • Practice good buoyancy control so you don’t bump into organisms.
  • Be mindful when surfacing about getting tangled in tentacles, which are often very hard to see.
  • Cover up! A wetsuit or even a thin Lycra suit is enough protection from accidental contact with these stinging creatures.

Need a wetsuit? Check out our buying guide or peruse our huge online inventory at ScubaToys, serving the Dallas area.

Have you been stung while diving or snorkeling? Let us know how you treated it in the comments below!

Video attribution: https://www.youtube.com/channel/UC98qLnGlZG9RLrv_zVsf32Q

Image attribution: https://www.flickr.com/photos/gocardusa/

Article Name
Ouch! Don’t Get Stung While Diving
Unfortunately, there are some sea creatures that may be beautiful to look at, but harmful to touch. We explore some of the more common organisms that divers may encounter that cause stings.

5 responses to “Ouch! Don’t Get Stung While Diving”

  1. Rika Trenton says:

    I grew up diving and snorkeling in Florida and the Bahamas, plus I’ve dove all over the Caribbean and other places. I’ve been stung the most in Florida! Portuguese man-of-wars often washed up on the beach and their tentacles would be in the water and on the sand – those hurt! I’ve also accidentally brushed up against fire coral while hunting lobsters and fish (usually while snorkeling). We used to sprinkle meat tenderizer on the stings – not sure it helped but I don’t ever remember the stings being that bad.

  2. Lori G. says:

    I was stung by a jellyfish while snorkeling once. It wasn’t my first sting, but it hurts pretty bad. I started keeping a bottle of vinegar in my bag just in case.

  3. Abe says:

    In 13 years of diving, I’ve never gotten stung by anything. I know some people who have, but I guess I’ve just been lucky.

  4. Tyler says:

    I haven’t gotten stung while diving but have been stung just from swimming in murky water. I think there is a big difference between being in water you can see in and being in water you can’t see in.

  5. Eric W. says:

    I was on a dive once and multiple people were stung. Even the guide told us this was extremely uncommon.

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