The electric blue waters of this pond in the Russian city of Novosibirsk has become the backdrop of many Instagram fans lately. Photographs of women in bikinis posing by the lakeside and visitors riding inflatable unicorns on the azure waters have gone viral on social networks. But authorities warn visitors not to be deceived by its appealing turquoise shade, because the lake is actually a toxic reservoir where chemical residue from a nearby power plant is dumped. The lovely color that reminds people of a tropical paradise is the result of a chemical reaction between dissolved calcium and metal oxides.

Local residents of Russia’s third largest city has begun calling the lake “Siberian Maldives”. Aside from the casual selfies, some have hired professional photographers for fashion and wedding shoots. There have been organized tours to the lake as well.

The Siberian Generating Company, which owns the plant, says the pond isn’t poisonous but the water is highly alkaline and can cause irritable skin rashes. On its social media outlets, the company advised visitors to exercise caution, imploring “not to fall into the ash dump in the pursuit of selfies.”

The lake is shallow—just one to two meters deep—and the bottom is muddy, which means that getting out of the reservoir without help is “practically impossible”, the company warned.

Photo credit: helenklem/Instagram

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Despite the warnings, visitors continue to flock the lake, and some even entered the waters. One woman who filmed a dreamy video on the lake soon paid a price.

“After visiting, my face was covered with a small rash,” she said. She also complained of “a dry throat and nose”.

Other visitors say that the soles of sandals flake off after walking along the water line. The water, many say, smells of strong detergent.

The lake is not natural, but was dug out to act as a dump site for chemical ash that results from burning coal at the thermal power station providing energy to to the city of Novosibirsk. Built in the 1970s, the power plant is largest of its kind in Siberia.

Photo credit: sup_novosibirsk/Instagram

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Photo credit: Ilnar Salakhiev/AP Photo

Photo credit: Ilnar Salakhiev/AP Photo

Photo credit: Ilnar Salakhiev/AP Photo

Photo credit: Ilnar Salakhiev/AP Photo