In early July, shepherds walking across the Tunisian desert, stumbled upon an unusual sight - a beautiful blue lake that had mysteriously appeared in the midst of the parched land. While nobody knows for sure how the 60-foot deep stretch of water that spans over two acres was formed, there are a few theories.

Some experts think that it may be the result of seismic activity, which ruptured the rocks above the water table and sent the liquid underneath, to the surface. Others believe it is rain water that has collected in the canyon. Of course to the hundreds of locals that have been flocking to what they call Lac de Gafsa or Gafsa beach, how the lake came into existence is irrelevant. What matters is that it provides them with much needed relief from the sweltering 40°C (104°F) temperatures.

Unfortunately, seeing them frolic in the lake is causing a great deal of concern amongst the scientific community around the world. That's because the area where the lake has magically appeared is known for its large deposits of phosphates that leave behind a radioactive residue. This means that there is a strong chance that the water is contaminated and most likely, carcinogenic. Moreover, the originally pristine blue lake is now infested with algae and has turned a murky green. Experts say this is a sign that the water is stagnant, making the lake a perfect breeding ground for parasites and diseases.

Even if the water is safe, there are concerns that if the lake was caused by seismic activity, the cracks in the rocks could result in the water flowing in the opposite direction, dragging swimmers with it.

While Tunisian officials did collect some water samples from the lake to test if it was safe about three weeks ago, they have not been heard from since. Meanwhile, neither their warnings to keep away, nor the murky green color, seems to be deterring the hundreds of locals that come to enjoy the cool waters of the miracle lake, every day.

Resources: weather.com, theguardian.co.uk, independent.co.uk