The turquoise hue of this lake in Siberia, Russia, has been attracting tourists in bikinis, couples and paddleboarders.
But dive a bit deeper and all is not what it seems.
Despite looking like paradise at first glance, the lake in Novosibirsk — nicknamed the Siberian Maldives — is actually an industrial dump.
The owner, the Siberian Generating Company, attributes the water's bright colour to calcium oxides — substances found in quicklime and harmful to humans — and the shallow water.
A spokeswoman told AFP that the site "isn't poisonous" but has very high acidity and that "the bottom of the ash disposal site is claylike, so if you fall there, it's hard to get out."
Local media reported on Friday that access had now been restricted by the company. "Any unauthorized visitors are prohibited from entering the area," it said over fears it would be difficult to rescue someone who fell in.
It had previously cautioned that the site is off-limits, writing on its website: "The territory is an industrial zone, not a nature reserve or aquatic park."
Still, it hasn't stopped Instagrammers from flocking to the site, with the best images then featured on the "Novosibirsk Maldives" account.
Alexei Cherenkov scored nearly 400 likes for a picture of himself on a unicorn float. He said he "went there for a pretty picture. Our city is grey and this is one of the available 'beautiful' places."
"The rash is gone already, but I would not recommend tasting this water," he added.