Attersee

The Attersee formed like every Salzkammergut lake, carved by the Traun glacier during the ice ages, and now covers 46.2 km2 and holds roughly 3.9 billion cubic metres of water at 469 m above sea level. Official maps put its deepest point at 169 m, and in 2014 divers reported finding a spot 172.6 m down, though that figure has not been independently confirmed. Larger lakeside settlements are Seewalchen and Schörfling to the north, Weyregg and Steinbach to the east, and Unterach, Nussdorf and Attersee am Attersee to the west, with the Ager river draining the lake north into the Traun and eventually the Danube.

More than twenty marked shore entry points ring the lake, maintained by the Tauchkompetenz-Zentrum Attersee, an association founded in 2006 by around forty local dive businesses; Weyregg alone has two dive centres. The entries range from flat training platforms with sunk cars and rowboats to steep walls and a field of drowned trees, and diving continues through winter, when the water is at its clearest. From the first Sunday of Advent to Candlemas on 2 February, a diving-club installation turns a submerged pile-dwelling model at Weyregg into an underwater nativity scene, built with students of HTL Vöcklabruck and described locally as unique in Europe.

The lake's reputation among divers is mixed with its risks. Rescue-service records list thirteen divers recovered dead between 1971 and February 2009 in the area of the Schwarze Brücke wall alone, and in 2005 Hans Brandstätter set an Austrian depth record here of 165 m. A landslide in September 1959 between Kammer and Weyregg pushed a stand of trees into the lake, and up to 20 m long trunks still lie in 15 to 30 m of water as the Unterwasserwald. Near the surface the lake warms to over 20°C in August, but below the thermocline it holds close to 4.6 to 4.9°C all year, so a drysuit is not optional once a dive goes past the first few metres.