If you've ever been to Las Vegas, you'll know pool parties are a big thing in Sin City... but an expert has warned you should probably skip going anywhere near the water.
For many vacationers, a trip to Vegas will involve spending some time trying your luck in the casinos, probably checking out one of the famous superclubs, and chilling out by the pool to top up your tan during the daytime, too.
And while the thought of sipping a frozen cocktail while cooling off in the water may sound pretty dreamy, what lurks in the pool might just put you off taking a dip.
Dan Kaszeta, a biological warfare specialist, has revealed what hidden nasties may be lurking in the pool water in Vegas.
Kaszeta, who was once a chemical Officer in the US Army and has worked with the Pentagon in the past, previously tweeted: "As a specialist in chemical and biological warfare, take this warning from me. Never get in a pool in Las Vegas. Don’t even touch the water."
He ominously added in a follow-up tweet: "I know certain things so that you don't have to."
After many followers - understandably - wanted to know more about exactly why they should not get in the tempting water, he explained he'd got a call from "another Federal agency" while working as "the chemical and biological terrorism guy at the White House Military Office" in around 1998 or 1999.
He said the man told him: "Dan, ya gotta help me. I'm working this case in Vegas. It's probably nothing but it could be a bio thing. But I need access to a lab that can keep this on the downlow until we know what the deal is."

Kaszeta put the guy in touch with people who could analyze various samples of the clear liquids, including control substances such as tap water and some water from a swimming pool from a "major hotel" to establish what was in the mystery sample.
He explained: "Two days later, I get a phone call in the middle of the night at home. From the White House switchboard. The lab is VERY eager to talk to me. Now, the lab, wisely and in accordance with good processes, did not know which sample was which. It turns out the "suspicious" liquid that had kicked off the investigation was something relatively harmless like glycerine.
"The sample that had one of the finest labs in the country alarmed so much was, erm, the control sample from the pool water. It was, to use a technical phrase 'a shop of horrors'."


He explained: "So, I asked the good scientists what was in this sample. They said it was easier to say what WASN'T in the sample. Alarming levels of Giardia and Cryptosporidium, both highly resistant to chlorine. A huge number of metabolites from human urine. Fecal matter, human, mammal, and avian. Trace amounts of cocaine, ketamine, and several different opiates. Adenoviruses. A weak immunochromatographic hit for Tularemia (not conclusive). Campylobacter. A soup of other things that I didn't even know existed."
He revealed that more samples from other pools in Las Vegas showed the same kind of thing, including bugs that were resistant to chlorine.
Kaszeta did not specify whether these things could be found in swimming pools in general rather than just in Vegas, but regardless, most people who travel to Sin City and take a dip manage to do so without getting sick, as long as they avoid ingesting the pool water itself.