In the Austrian town of Tragoess, Styria, the picturesque peaks of the Hochschwab mountains stand sentinel around a body of water whose name, Grüner See, literally translates as Green Lake. The lake, whose shimmering emerald waters live up spectacularly to its name, is a popular attraction amongst hikers and nature enthusiasts for the majority of the year…until spring’s arrival turns it into a diver’s playground. During autumn and winter, the lake measures just 3-6 feet/1-2 meters deep, but as the snow on the surrounding mountains melts, the basin that contains the lake begins to flood. Between mid-May and June, the Grüner See reaches depths of up to 40 feet/12 meters, submerging the adjacent parkland. While this flood season makes the park inaccessible to those on foot, it does transform it into a unique wonderland custom-made for scuba exploration.
With the entirety of the park underwater, divers are able to fin along pathways lined with still-flowering alpine plants. Plains of gently undulating grass studded with trees are suddenly on the bottom of the lake, their boughs home to iridescent trout rather than birds. Thanks to mountain meltwater’s clarity, the lake’s visibility often reaches 130 feet/40 meters, but due to the lake’s vastly fluctuating water levels throughout the year, there’s not much life to be seen with the exception of the trout and some small crustaceans. But the novelty of soaring weightlessly above park benches and bridges more than makes up for the lack of fauna. To dive the Grüner See is a unique experience, comparable to finding oneself suddenly plunged into a Dali painting — something that must be seen to be believed. There is a very brief window of opportunity for those wishing try it though: by July, the lake has already begun to recede back to its normal level.
The lake’s shallow depths mean that this dive is accessible to all divers, regardless of certification level or experience. However, a lake created by glacial flooding makes for predictably frigid conditions, so divers should expect temperatures between 39-45F/4-7C. Make sure to wear suitable exposure protection, and have warm clothes ready and waiting upon surfacing. That way, you won’t have to wait for your teeth to stop chattering before sharing your tales of a rather extraordinary day in the park.