As a hot summer rages through North Africa, Tunisians have discovered a mysterious body of water that never existed before. Officials have warned locals to stay out of the unexplained lake, but wanting to escape the heat, local residents have jumped in.

Around three weeks ago the lake appeared near the city of Gafsa in southern Tunisia, according to France24, and now locals have been bathing in its waters. When it first appeared, the lake's waters had been a pristine turquoise, but after a few days, they turned a murky green.

Local officials warned people on Monday not to enter the lake known as Lac de Gafsa, or Gafsa Beach because no one knows what the waters contain yet. Public safety director Hatef Ouigi told France24, told that the warning was a precaution until inspectors "verified the water's quality."

According to the Guardian, the region in which the lake has appeared has been used for the mining of phosphate since the late 19th century. Tunisia is currently the world's fifth largest exporter of the element, the newspaper said.

When shepherds first discovered the lake, it was believed to be miraculous, but scientists now posit that seismic activity may have ruptured the bed of water, leading to water rising from below.

"This region is overflowing with large deposits of phosphate, which can leave behind radioactive residue, so there is a real risk that the water is contaminated and carcinogenic. There's no security of any kind," wrote Lakhdar Souid, a Tunisian journalist writing in the Tunisia Daily newspaper, via the New York Post.

However, Tunisians continue to swim in the lake, thanks in part to a Facebook page with now more than two thousand "likes."

Souid said that the water has turned green, a sign that there is no water movement and algae are growing, which could mean the presence of bacteria. However, bacteria may be the last concern.

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