(CNN) — Instagrammers have been warned not to dive into an idyllic-looking, turquoise lake in northern Spain , because its toxic waters could lead to health issues.

Monte Neme, in the northwestern Spanish region of Galicia, offers a stunning setting for Instagrammers looking for the perfect selfie.

But, not for the first time, the pursuit of envy-inducing images is leading to risky behavior.

The site is actually a water-filled open pit from a disused mine and its waters are contaminated with toxic chemicals.

It was mined for tungsten and tin from 1915 and for quartz and construction aggregates in the 1980s, Ramón Varela, journalist and spokesman for the local Salvemos Cabana environmental group, told CNN.

He said that Galicia's water agency had confirmed its composition had very high levels of aluminum and a low pH, meaning the lake was acidic.

While there haven't been any serious accidents yet, medical authorities have warned people against diving into the tempting waters for safety reasons.

"Bathing for a brief time could cause irritation to the skin and the eyes while drinking the water could cause colic, diarrhea and vomit," Manuel Ferreiro, doctor at the nearby A Coruña hospital, told CNN. "Those are not very serious problems, but the water is contaminated."

He added that the turquoise color is due to the pit's silica sand, which is not itself toxic.

But these warnings didn't stop Instagrammers from posting pictures of themselves diving into the quarry.

One Instagrammer who recently shared a picture of the pit, Antonio Outeiriño Lopez, told CNN he took the picture of the lake in 2015, before it became a social media sensation.

He said he is aware of the toxic nature of the lake and didn't think about swimming in it. "I'm not an ignoramus who exchanges life for a like," Lopez said. "The place is beautiful, but it shouldn't be open to the public."

According to Varela, another hazard lies in the surrounding slopes, which in some places drop off for more than 30 meters.

"The place is very dangerous, there is only one sign in the whole complex and it is an area where families sometimes get close," he added.

Salvemos Cabana has called on the Galician authorities to seal off the quarry.