Instagram users have been warned against swimming in a popular lake near the Russian city of Novosibirsk because it serves as an ash dump for a nearby coal plant.

The location has become popular on Instagram for its vibrant blue water, which is caused by the metal oxides dumped in it from the plant.

The water is not poisonous but could cause an allergic reaction.

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Crystal-clear turquoise water against the backdrop of a clear blue sky along the beach may very well be the makings of a perfect Instagram post. But one lake near the Russian city of Novosibirsk that has recently become popular on Instagram may not be the paradise it seems.

Instagram users have been warned against swimming in the body of water, a man-made lake nicknamed the "Novosibirsk Maldives" because its vibrant blue color comes from metal oxides dumped in it from a nearby coal plant, according to recent reports from CNN, The Moscow Times, and Mashable.

The Siberian Generating Co., the firm that runs the coal plant that built the artificial lake, issued a warning on the Russian social-media platform VKontakte last month. According to a translation of the post, which described the lake as an "ash dump," the water is not poisonous, but it is also not suitable for swimming. Contact with the water could cause an allergic reaction, and the muddy bottom of the lake could make it difficult to get out.

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Photi: @_yuliya_kostyuchenko_ A post shared by 🌴Новосибирские Мальдивы 😎🌴 (@maldives_nsk) on Jul 7, 2019 at 10:25pm PDT Jul 7, 2019 at 10:25pm PDT

The location has become such a popular location on social media that it has its own Instagram account, The Moscow Times said, which is filled with images of people posing near the radiant water. Most Instagram posts published to this account show people near the water rather than in it, although some people have been seen in the water on paddle boards or pool floats.

Работяги, плавать там не опасно🚨 На следующее утро мои ноги слегка покраснели и чесались дня два, потом все прошло 🙏🏽 Но что не сделаешь ради таких снимков😋Вода на вкус немного кисловата, похожа на мел 😝 #новосибирскиемальдивы #золоотвалтэц5 #золоотвал #золоотвалнск #тэц5 A post shared by Alex (@tweezer_nsk) on Jul 3, 2019 at 7:15pm PDT Jul 3, 2019 at 7:15pm PDT

Those visiting the lake, however, don't appear to be very concerned. A translation of a caption under an Instagram photo showing a man riding a unicorn pool float with his feet in the water said, "It's not dangerous to swim there. The next day, my legs turned slightly red and itched for about two days." Another caption under an image of two people on paddle boards translated to: "By the way — the last chemical analysis of the water showed that it is not so dangerous."