Achensee is Tyrol's largest lake, tucked between the Karwendel range and the Brandenberg Alps, sometimes nicknamed the 'Tyrolean Sea' thanks to its size and the steady winds that make it a favorite among sailors and windsurfers. The water here is remarkably clear, with visibility reaching up to ten meters, and temperatures rarely climb above 20°C even in summer.

The scenery around the lake is one of striking contrasts — steep limestone cliffs of the Karwendel plunge into the water on the western shore, while the eastern side slopes more gently toward the Brandenberg Alps. The western shore is accessible only on foot, along a narrow trail hugging the rock walls, while the eastern shore is served by a scenic road with tunnels offering glimpses of the water and peaks. In winter the lake settles into quiet stillness, while summer brings sailing regattas and lakeside hikers.

• Pertisau — trail along the western shore to Achenkirch (Scholastika), paved at first, then a narrow path (Mariensteig) with sections of steps leading to Gaisalm, requiring good footing and no fear of heights, moderate to demanding difficulty
• Maurach or Jenbach — reach Seespitz station via the Achensee cog railway, then continue on foot or by lake steamer

• The lake lies within a protected nature area, so fuel-powered motorboats are not permitted
• Gaisalm is a staffed mountain hut with its own boat landing
• The Gaisalmsteig section toward Scholastika is partly secured with steel cables and requires a steady head for heights

One curious fact: the lake trout here spawn not in tributary streams but directly in the lake itself, at depths of 10 to 15 meters — a rare behavior among alpine lakes.