Bodensee Längsquerung 2026

Stretching across international borders between Germany and Austria, the longitudinal crossing of Lake Constance demands between 64 and 68 kilometres of continuous open-water swimming. The Bodensee Längsquerung is an open water lake marathon organised by Bodenseequerung®, linking the German shore of Bodman in Baden-Württemberg to Bregenz in Austria, or vice versa depending on weather and currents. Held in June, the event tests endurance over an official distance of 64,000 metres across the expansive waters of the lake. Undertaking the crossing requires excellent physical fitness and methodical endurance training. Swimmers must adhere strictly to the official regulations established by Bodenseequerung®. During the swim, any physical contact with the escort boat or the accompanying crew is strictly prohibited. Every feed must take place entirely in the water, requiring swimmers to tread water while taking on nourishment from the support team.

Lake Überlingen: glacial depths and alpine molasse rock

The initial stretch of water leads through Lake Überlingen, which forms the northwestern arm of Lake Constance. Resting at a water surface elevation of approximately 395 metres above sea level, this arm originated as a rift valley formed during the folding of the Alps. During the Würm ice age, the Rhine Glacier shaped the basin, and throughout the Constance stage of the glacial withdrawal it was a glacial lake containing floating icebergs. The rocky walls enclosing this part of the lake are composed of molasse, a soft tertiary sandstone. Below the surface, Lake Überlingen reaches a maximum depth of 147 metres. At Sipplingen, the Bodensee-Wasserversorgung water supply maintains an intake point positioned at a depth of 60 metres. Navigating this glacial rift places swimmers between steep sandstone slopes and profound depths that extend far beneath the stroke.

The submerged Teufelstisch rock needle and deep shelf

Along the Überlinger See is a striking geological formation known as the Teufelstisch. This underwater sandstone needle features a flat plateau measuring approximately 22 by 10 metres. The plateau typically remains submerged between 1.5 and 3 metres below the water surface. A narrow underwater ridge at a depth of about 32 metres connects the rock formation directly to the Bodanrück shelf. On the open lake side, the rock wall of the Teufelstisch drops almost vertically to a depth of roughly 90 metres. In exceptional low-water years such as 1823, 1909, and 2006, when lake levels dropped below 2.30 metres, the stone table emerged completely from the water.

The Bodanrück peninsula: Marienschlucht cliffs and Hörnle point

The Bodanrück is a 112-square-kilometre peninsula that divides the northwestern part of Lake Constance into Lake Überlingen and the Untersee. The peninsula presents a landscape of orchards, pastures, forests, and diverse moor and reed areas. Along its northeast side, the Marienschlucht gorge cuts deep into the molasse rock, having carved an incision approximately 100 metres deep through the cliffs toward the lake shore. At the easternmost point of the Bodanrück lies the Hörnle, a headland that marks the northeastern boundary of the Konstanzer Trichter. Protected nature reserves line the shores of the peninsula, including the Wollmatinger Ried, a wetland area of reeds that has been safeguarded since 1938. Adjacent to this reed reserve, between the Gnadensee and the Untersee, sits Reichenau Island, with a land surface of 4.3 square kilometres and an 11-kilometre circumference.

Inhabited since the Bronze and Iron Ages, the island has been connected to the mainland since 1838 by a causeway, which is intersected near the ruins of Schopflen Castle by a 95-metre-long waterway called the Bruckgraben. In the peninsula's drumlin landscape also lies the Buchensee, the largest of three small glacial remnant lakes, covering three hectares with a maximum depth of twelve metres. Named for its shape resembling a beech tree, it borders the Buchenseen nature reserve adjacent to its swimming area. About ten kilometres from the race area, another finger of land extends into the lake: the Mettnau peninsula.

Measuring 3.5 kilometres long, up to 800 metres wide, and covering 140 hectares, Mettnau lies between the Markelfingen corner to the north and the Zeller See to the south. Its nature reserve was established in 1926 and expanded to its current size in 1984. A pond on the peninsula was created accidentally from a former landfill, and because it is independent of Lake Constance water fluctuations, it provides a dedicated hatching site for ducks. The reserve also encompasses Love Island, situated approximately 200 metres south of the Mettnau shore.

Bodman: pile dwellings and imperial lakeside palace

The starting point in Bodman sits on the westernmost shore of Lake Überlingen, which forms the north-western arm of the Upper Lake. Bodman preserves prehistoric pile-dwelling settlements that are recognized as a UNESCO World Heritage Site. During the early Middle Ages, Bodman served as a Frankish imperial palace, an Alamannian ducal seat, and a mint. Latin sources starting from 833 or 834 AD referred to the surrounding region and the lake as lacus potamicus. Setting out from Bodman's historic shore to swim toward Bregenz leads athletes across sixty-four kilometres of freshwater history, tracing the full length of the lake.