The Allgäu Triathlon begins and concludes at Großer Alpsee in Immenstadt, located in Germany's Allgäu region. It takes place annually in August as a swim-bike-run event featuring multiple race distances. The triathlon has been hosted here since 1983, establishing it as Germany's longest-running triathlon and one of Europe's oldest. The primary L race approximates a middle distance, comprising a 1.9 km lake swim, an 84 km road cycling segment, and a 20 km road run. Shorter distances are available with the M race, which includes a 1.5 km swim, a 42 km cycle, and a 10 km run, and the S race, covering 500 m, 27 km, and 5 km. The M distance is also offered as a relay.
The course presents a significant challenge: the Allgäu roads involve substantial climbing, and Kalvarienberg is a notable feature athletes encounter. Approximately 2,800 participants compete, with amateur racers competing alongside elite triathletes. Thousands of spectators gather around the lake area, transforming it beyond a simple start-and-finish location. The race was initiated by German Altenried, and the 808project team currently manages it. Its history includes hosting a World Championship, two European Championships, and eleven German Championships. The event maintains a strong local identity, using the hashtag #kultseit1983, referencing the sport's Hawaiian origins, and recognizing its volunteer crews as essential to the race.