Gruner see, the lake that lives only 4 months

In Styria, a region in southeastern Austria with Graz as its capital, there is a unique lake. To tell the truth, it doesn't even exist all the time: only four months of the year you can admire it, and its history is incredible. It is the Grüner See, and to see it, you need to arrive in Tragoess in spring. Depending on the season, it is either a lake or a park. The panorama always changes only in spring, when the melted snow from the surrounding mountains - and fed by underground springs - flows into the basin in which the park stands, transforming it into a spectacular alpine lake. So, armed with wetsuit and oxygen tank, divers dive into its waters ready to live an experience that promises to be unforgettable. They can walk along the park's paths, cross its bridges, sit on a bench and caress the grass. Everything, of course, below water level. A water that, thanks to the presence of grass and leaves underneath, has a very special green colour.

In July, however, the lake quickly disappears. A small river takes its water away, and the park returns to the surface. Until the following spring.