Picture courtesy of Britannica

 

Phuket's Kata Noi Beach is under watch after venomous sea critters, including the notorious Portuguese man o’ war, appeared on shore. Known locally as the “floating terror,” this creature is not to be trifled with.

 

The Department of Marine and Coastal Resources (DMCR) sounded the alarm after lifeguards alerted them on 15 July. The Andaman Sea and Coastal Resources Research Center confirmed the presence of several hazardous species, sparking concerns.

 

Among the newcomers are the Portuguese man o’ war, deceptively resembling jellyfish but actually siphonophores armed with a painful sting. Despite their small size—just one to two centimetres—their sting can cause serious discomfort.

 

The spectacle doesn’t end there. Blue sea dragons, or Glaucilla sp., often mistaken for harmless visitors, also washed ashore. These electric-blue creatures carry venom borrowed from jellyfish, delivering a nasty zap to swimmers.

 

Keeping them company are less dangerous, yet still pesky, blue button jellyfish and by-the-wind sailors (Velella velella), which can irritate the skin upon contact.

 

Experts attribute this aquatic invasion to recent turbulent seas. Strong winds and waves, reaching heights of two metres, likely pushed these creatures to shore. Over at Karon Beach, similar sightings continue, keeping lifeguards busy monitoring and recording any unfortunate encounters.

 

To prevent mishaps, monitoring teams are in action, armed with first-aid leaflets advising victims of stings to rinse with vinegar while avoiding freshwater or rubbing the area.

 

DMCR officials warn, “Seek medical help immediately if stung.” With jellyfish blooms often stirred by seasonal shifts and warming waters, further incidents are anticipated.

 

Tourists heading to Kata, Karon, and neighbouring beaches should heed warnings: check beach flags and consult with lifeguards before entering the water. Authorities are urging all beachgoers to give any mysterious marine life a wide berth, both on the sands and in shallow waters.

 

Precautions are being amplified. Warning signs are sprouting up, lifeguards are ever vigilant, and safety advice is circulating across local channels, involving tourists, locals, and beachside businesses.

 

As the situation evolves, officials emphasise staying informed and cautious. Beach visits in Phuket currently demand a blend of curiosity and care—look, but don’t touch, to ensure a safe seaside experience.

 

  Adapted by ASEAN Now from The Thaiger 2025-07-17

 

 

Portuguese Man O' War  - venomous sea creatures, foreigners having sex on the beaches, boats capsizing and Indians sleeping and defecating on the beaches, Phuket sounds like a real hell hole.

I used to own a boat and sail across Pang Nga Bay, then enjoyed swimming a bit around the boat, but at one point I had a sea snake as an oncoming, haven't swam much there since then anyway, unfortunately.
And with the knowledge that “Portuguese Man O'War” swim there too, you have to be even more careful.

15 hours ago, snoop1130 said:

Phuket's Kata Noi Beach is under watch after venomous sea critters, including the notorious Portuguese man o’ war, appeared on shore. Known locally as the “floating terror,” this creature is not to be trifled with.

The old "blue bottle", used to turn up in the hundreds on occasions on the NSW beaches. Is vinegar still the go for treating the sting or do they suggest something else these days.

15 hours ago, snoop1130 said:

Phuket's Kata Noi Beach is under watch after venomous sea critters, including the notorious Portuguese man o’ war, appeared on shore. Known locally as the “floating terror,” this creature is not to be trifled with.

That would really spoil your day

There is or used to be a "season" for these off Sabah. Add to that the locals used pink plastic bags and it was difficult to tell which was which when riding around on a SurfJet.

My then wife was stung by one and she said it was more painful than child birth. For years the sting mark would turn red if she went into the sea.

 

Maybe it is also a seasonal thing here, also.

17 minutes ago, VocalNeal said:

Maybe it is also a seasonal thing here, also.

Yes it is , with the currents and the season.

16 hours ago, snoop1130 said:

not to be trifled with

 

1 hour ago, Formaleins said:

Portuguese Man O' War  - venomous sea creatures, foreigners having sex on the beaches, boats capsizing and Indians sleeping and defecating on the beaches, Phuket sounds like a real hell hole.

I assume it is the recipe for a good family destination just like Pattaya is.

Blue bottles... Yep they tend to sting a bit.  Not sure which is worse that or a hornet sting. 

 

Had both and neither was enjoyable. Hornet sting lasted longer. 

2 hours ago, Formaleins said:

Portuguese Man O' War  - venomous sea creatures, foreigners having sex on the beaches, boats capsizing and Indians sleeping and defecating on the beaches, Phuket sounds like a real hell hole.

Bar flies be safe no Portuguese men I war there. They couldn't afford the exorbitant prices.😀

The sting from the Portuguese Man's War or Blue Bottle can even be fatal. Tentacles can be up to 30 meters long. Stear well clear!

3 hours ago, Peterphuket said:

I used to own a boat and sail across Pang Nga Bay, then enjoyed swimming a bit around the boat, but at one point I had a sea snake as an oncoming, haven't swam much there since then anyway, unfortunately.
And with the knowledge that “Portuguese Man O'War” swim there too, you have to be even more careful.

 

Sea snake while deadly are not the least bit aggressive

Authorities say give any mysterious creatures a wide berth.

How are you supposed to spot a 1 - 2 cm jellyfish  swimming underneath you?

I believe it’s box jellyfish that you have to be careful about. Their sting can kill.

 

i was due to do a triathlon once and the swim section was cancelled due to a box jellyfish fish sighting. Another time people were getting stings, but they were normal jellyfish and it just stung a bit for a short while.

 

Whichever, I don’t imagine it’s great for tourists, even if the waves are too big to swim and it’s raining in any case.

 

Low season holidays 🙄

4 hours ago, KannikaP said:

Authorities say give any mysterious creatures a wide berth.

How are you supposed to spot a 1 - 2 cm jellyfish  swimming underneath you?

Obviously not a beach person. The blue bottles float on the surface and can be 10 cm back home. Have been stung many times and they can leave a welt for a while. They can be fatal if they get you around the throat.

47 minutes ago, GreasyFingers said:

Obviously not a beach person. The blue bottles float on the surface and can be 10 cm back home. Have been stung many times and they can leave a welt for a while. They can be fatal if they get you around the throat.

No, I am not a beach person except when it comes to the Beach Boys I am.

It was in response to the OP to which mentioned the 1 - 2 cm. I've no idea how small, or big, or dangerous they can be. 

Same every year...

On 7/18/2025 at 1:33 PM, wensiensheng said:

I believe it’s box jellyfish that you have to be careful about. Their sting can kill.

 

i was due to do a triathlon once and the swim section was cancelled due to a box jellyfish fish sighting. Another time people were getting stings, but they were normal jellyfish and it just stung a bit for a short while.

 

Whichever, I don’t imagine it’s great for tourists, even if the waves are too big to swim and it’s raining in any case.

 

Low season holidays 🙄

Indeed , box jelly fish are the big danger in South East Asia . 60-70 people die each year in the Philippines . Also 5 deaths is Thailand since the 1990s, mostly around Koh Samui area .  Box jelly fish are difficult to see as they are translucent . Often in shallow waters . Can kill in seconds or up to 48 hours after a sting . Vinegar application asap and sting removal with tweezers can help . Many Thai beaches have vinegar stations . Some beach hotels have nets in the sea to prevent jelly fish entry . One of the reasons that Thai people are often seen swimming fully clothed , is to prevent stings . 

Most European tourists are unaware of the dangers in swimming in Thailand's seas , both in the Andaman sea and the Gulf of Thailand . Not only sea creatures but also rip tides etc .