Several people in Spain reported falling ill after bathing in Monte Neme — a toxic dump in Galicia, northern Spain — after mistaking it for an Instagram-friendly turquoise lake.
Monte Neme is an abandoned quarry, which was in use from 1975 to 1980, and was once connected to a tungsten mine.
The region has attracted scores of tourists over the years owing to the distinct blue waters of six such reservoirs, only a few of which hold water during the summer. The exquisite colour of the water is actually a result of chemical contamination.
Some Instagrammers said they had skin irritations and stomach problems.
"Beyond the health problems that can result from recreational activities in a mining lake, it is a personal security problem because there may be falls, even fatalities," Ramón Varela, environmental journalist and spokesperson for Salvemos Cabana, an association for the protection of natural and cultural heritage in the area, told Euronews.
He said the group asked the regional government of Galicia to put security measures in place and to prohibit entry to the area to prevent serious accidents.
"At the weekend, it's a kind of pilgrimage and it's a dangerous place because it's a landscape caused by industrial liquids," says Varela. "On the one hand, it is an area that's easy to access and, on the other, the slopes are risky, reaching heights up to 30 metres."
It's not just the quality of water that is dangerous, according to Varela, as there is an area of mud in which people could potentially get trapped.
Salvemos Cabana said it was unfortunate that there were security problems even when regional legislation exists that says abandoned mining complexes must not be left abandoned.
Varela explained a serious incident occurred in the area in 2014, when one of the "lakes" at the complex burst its banks, releasing a toxic spill measuring 24,000 cubic metres.
"The Xunta de Galicia (regional government) should have tried to resolve the problem at Mount Nemen long ago. We have been asking for it to be sealed off and drained," he said.
An image of the reservoir was even used in an advert for tourism in the region. "This is a mining landscape, which is devastated and unrestored but Galicia used it to promote tourism in the region as if it were an idyllic landscape," Varela said.
Euronews contacted the Xunta de Galicia for comment but it had not replied at the time of publication.
It is not just Instagrammers in Spain who have been enticed by a seemingly picturesque landscape. The turquoise hue of lake Novosibirsk in Siberia, Russia, also attracted tourists. At first glance, the water looks crystal clear, with the lake dubbed the Siberian Maldives, but it is actually an industrial dump.
Its owner, the Siberian Generating Company, attributed the bright colour of the water to calcium oxides — substances found in quicklime that are harmful to humans — and the shallow water.
Instagrammer Alexei Cherenkov posted a picture of himself crossing the polluted water on an inflatable unicorn. He said he went there to get a nice picture because his "city is grey and this is one of the most beautiful places available."
"The rash has already disappeared, but I would not recommend testing this water," he lamented of his experience.