...and totally submerges the surrounding park when temperatures rise again.

Gruner See in Austria
Credit: Getty Images/Westend61

Nature has formed plenty of water features that seem anything but natural: these bubblegum-pink lakes in Australia, the terraced Travertine pools of Turkey, and a blood-red waterfall in Antarctica. But this lake has an even cooler trick: at the same time every year, it overflows to seven times its depth and then “disappears almost completely” on its own.

Grüner See, which translates to Green Lake, is located in the Hochschwab mountains of Styria, Austria, near the village of Tragöess. It’s quite the picturesque spot, frequented by locals for hiking and relaxing on benches until about mid-June, when those trails and benches are under up to 36 feet of water.

As temperatures rise in the spring, the snow from the surrounding mountains melts down into the basin — which has a pond year-round that’s only 3- to 7-feet deep during the winter — completely flooding tree trunks, trails, benches, and even a little foot bridge.

The natural phenomenon creates an almost surreal underwater park until July, when the water begins to evaporate again, restoring park access to land lubbers. Because the water is snowmelt, it’s incredibly cold (usually no warmer than 45 degrees Fahrenheit) and incredibly clear. This high visibility (up to 160 feet) is actually what lent the lake its eponymous color — and eventually its nickname: the “Caribbean of the Alps.”

Not surprisingly, the appeal of a magical, emerald-toned lake attracted a few too many tourists, becoming a hotspot for divers. This prompted the local tourism office to look into imposing similar restrictions enforced in bioluminescent bays around the world that are endangered due to widespread human interest.

According to Dive Magazine, the tourism office made an announcement on its Facebook page officially prohibiting all watersport activity in 2016; that means no diving, swimming, or boats allowed in the waters of Green Lake. The decision was made after consulting with multiple experts and determining the risk of stirred-up sediment could potentially pollute the lake’s vibrant color.

As thousands of Instagram posts prove, the lake is just as stunning to experience from the surface, and doing so will ensure it continues to be for years to come. And there’s a recreational lake a 10-minute drive away, Lake Zenz, should you find yourself itching to dive in.

Before planning a visit, you can check the current water level on the park’s website.