Gruner Sea , or the Green Lake, is situated in the foothills of the Austrian Hochschwab Mountains, close to the resort town of Tragoess in Stryria. It is considered one of Austria&’s treasures and looks completely different from season to season. During spring, an unusual phenomenon happens when the winter snow melts.

The snowmelt makes its way down the mountainous area, submerging the surrounding forest so that the area becomes an underwater fantasy land. In 2006, the surrounding area was declared a nature reserve, so no camping or fires are permitted in the area. Despite this, the site attracts many tourists, who enjoy scuba diving in the fleeting underwater wonderland.

You can dive for about a month during the spring, although the water has an icy temperature of four- eight degrees Celsius.

The snowmelt has a crystal clear quality, making for fantastic visibility and images of a surreal otherworld. During the winter months, the scenery transforms and the area is decorated with snowcapped mountains. Locals enjoy hiking the forests and meadows in the area, and yodelling can be heard.

This yearly transformation lasts for only a few weeks and sees the lake double in size, from 21,500 to 43,000 square feet.

Every spring the snowmelt floods the shallow winter lake, raising it by 10 meters. In the winter, the lake almost disappears, with a depth of one- two meters.

The area has earned the honour of being Europe&’s top underwater location.

Scuba divers can swim around and see the submerged grass, footpaths, bridges, benches, trees and flowers, all intact, along with snails, trout, water fleas, fly larvae, and crabs.