Pictures make it look like a pristine and beautiful sea, with azure waters like you find in the Caribbean.
So no wonder influencers are flocking to this lake in Russia.
Theres just one problem: Its actually a dump for harmful ash from a nearby thermal power station.
Its bright blue colour comes from metal oxides and calcium salts dissolved in the water.
The Russian power plant which owns the lake urged people to stop swimming in pursuit of the perfect picture.
Siberian Generating Company warned online: You can not swim in the ash dump. The water in it has a high alkaline environment. Skin contact with such water may cause an allergic reaction!
They said the bottom of the lake was extremely muddy and that getting out is almost impossible.
In capital letters, they urged: THEREFORE, WE ASK YOU VERY MUCH THAT IN YOUR QUEST FOR A SELFIE YOU DONT FALL DOWN INTO THE ASH DUMP! THIS IS THE BIGGEST RISK.
One man posted a photograph of himself wearing a balaclava and riding an inflatable unicorn in the lake.
Clearly not taking the warnings too seriously, he wrote: Its not dangerous to swim here. The next morning, my legs turned slightly red and itched for two days, but then everything went. But what wouldnt you do for the sake of such pictures?
He added that the water tastes a little sour.