"DO NOT swim in the ash dump. The water is highly alkaline," the company recently wrote on Russian social network VKontakte. "This is because calcium salts and other metal oxides are dissolved in it. Skin contact with such water may cause an allergic reaction!"

It added that the bottom of the lake is muddy, so those who do dare to wade in might get stuck and unable to free themselves. The water's pH is above 8, SGC said, though it claimed the water wasn't poisonous. In case the warning wasn't clear enough, the company wrote in all caps, "THEREFORE, WE ARE ASKING -- DON'T GET INTO THE ASH DUMP IN THE PURSUIT OF A SELFIE."

Despite that, some ardent Instagrammers remain undeterred, with some posting photos of themselves floating on inflatable toys and paddling in the toxic water. One even joked that "the water tastes a little sour."