The lake basin was carved out by the Iller glacier during the Würm glaciation period.
The water depth reaches a maximum of 19 meters.
Großer Alpsee is part of the 'Nagelfluhkette' Nature Park, which is the first German-Austrian transboundary nature park.
The lake serves as a significant stopover and breeding ground for various species of waterfowl due to its reed belts.
The term 'Nagelfluh' refers to the unique conglomerate rock formation of the surrounding mountains, resembling a 'nail-studded' surface.
Großer Alpsee is the largest natural lake in the Upper Allgäu region, situated at an altitude of 724 meters. Spanning approximately 2.4 square kilometers, the lake is fed primarily by the Konstanzer Ach and drains into the Iller river. The area is a designated protected landscape due to its diverse moorland and wetland habitats. Visitors access the water via several designated bathing areas, including the Strandbad in Bühl. The lake experiences thermal wind patterns, making it a reliable location for sailing and windsurfing. The surrounding topography features the Nagelfluhkette mountain range, providing a distinct backdrop to the glacial lake. Various watercraft, including pedal boats and rowboats, are available for hire to explore the perimeter. The water quality is consistently monitored, maintaining high standards for recreational swimming throughout the season.
The elevated viewing point along the southern path looking north towards the village of Bühl with the Alps in the background.
Use the dedicated wooden jetties for easier entry into the water, as the shoreline can be pebbly.
Bring polarized sunglasses to reduce water glare, which is helpful for spotting fish or submerged aquatic plants.
Combine your visit with the circular hiking trail that encompasses the entire lake perimeter for a full view of the Nagelfluhkette.
Attempting to swim near the mouth of the Konstanzer Ach, where water temperatures are significantly lower and currents can be unpredictable.
Bathing facilities and boat rentals typically operate only during the warmer months from May through September.
Respect protected reed zones by not swimming or boating near them; use designated beach entries to prevent soil erosion.
