Update: As of 2018, scuba diving is no longer allowed in Green Lake.

Located in Tragoess, Styria at the foot of Austria’s Hochschwab Mountains, Green Lake (Grüner See) expands each spring as mountaintop snow and ice melt, creating an underwater nature park.

Dubbed Green Lake for its emerald waters, it offers you a chance to scuba dive around sites that are usually on dry land, including its meadows, trails, roads, and bridges. You can see fish swimming through the branches of trees – a surreal effect.

When to go: The underwater park exists for half of the year, but late spring and summer are the best times to explore; the lake can be up to 30 feet deep from mid-May to June. By the end of July, the water recedes and you'll have to explore the park with hiking boots instead of scuba gear. It's a one-hour drive from the Graz Airport.

What to do: After exploring Green Lake, your adventure doesn't have to stop there. While in Styria, dubbed Austria's "Green Heart" for its dense forests, hike or cycle the rest of the Hochschwab mountain range. Rest at one of area's many hiking hotels or travel out to a thermal spa to revitalize before heading home.