DW: A lake dubbed "Lac de Gafsa" has appeared in Tunisia. What can you tell us about this body of water?

Naveena Kottoor: It's in southern Tunisia, about 25 kilometers from a place called Gafsa. The region is quite well known because it's where phosphate is mined. The lake is about a hectare in width, and it's believed to be between 10 and 18 meters deep. It's not entirely clear yet how this water has appeared and how this lake has formed. Shepherds reportedly discovered this lake in the desert about three weeks ago. Since then pictures have emerged and people are going swimming there, but it's desert terrain, so it's quite unusual for this amount of water to appear in the middle of a desert.

Is there an explanation for how the lake has suddenly emerged in such a dry area?

No, not yet. Local scientists are in the process of trying to find out what exactly happened. There are some theories that there might have been a very, very small earthquake that caused a tremor and ruptured the rocks, and that water rose to the top and filled up the space that was there. Another theory is that the lake just filled with rain water and it took people a long time to discover it. But it's not entirely clear where this water is from and how this lake has formed.

How remote is this particular region where the lake was discovered?

Well, it's in the middle of the desert and it's very hot, which might explain why people might not have been walking around that part of Tunisia at this time of the year. It's really very hot here, and especially down in the south it's around 40 degrees Celsius, so you can understand why it would take a certain amount of time for this lake to be discovered.

How have locals reacted to the news of the lake?

I think they are quite happy. It's a great opportunity to cool down. Ramadan just came to an end about a week ago, it's very hot here at the moment, and it's holiday time. So I think people are enjoying the fact that they have access to this lake and can go for a swim.

There are pictures of people jumping off the cliffs into the water, swimming. I have to say that the local authorities are warning against swimming because it's not entirely clear how safe the water is. The main concern is that - because it's a phosphate mining area - the phosphate residue might still be in the water and might be radioactive. So people have been told to stay away from the water and from the lake, but they have been largely ignoring those warnings.

Have there been any signs of illness in the local population as a result of the water?

No, not yet, but that could also take a while. We don't have any reports of people falling ill. It is the phosphate mining area in the country, and that's why the authorities are telling people to stay away from the water until it's clear whether it's safe to swim there. The other problem we have is that this water has turned from turquoise to muddy green and that suggests that the water isn't changing and that the lake isn't being replenished. That could also mean that diseases and bacteria can grow, especially at this temperature.

Naveena Kottoor is a journalist based in Tunisia.