Salzachdurchbruch, Water gap on the Salzach in Hochburg-Ach, Austria

The Salzachdurchbruch is a sediment outcrop on the bank of the Salzach at river kilometre 11.3 in the municipality of Hochburg-Ach, Upper Austria. Since the last ice age the river has cut about 70 metres into the Flinzsand, leaving a steep slope with numerous caves. Fossil leaf imprints and lignite seams in the rock record former swamp forests.

After the last ice age the Salzach cut about 70 metres into the Flinzsand, leaving the steep bank with its caves. After a huge flood in 1923, artificial bank structures were built to regulate the current, including a dam of granite stones in mid-river known locally as the "Hund" or "Wolf", meant to stop the current eroding the slope.

The caves in the steep bank shelter Aesculapian snakes, jackdaws, bats and eagle owls. The rock face also holds fossil leaf imprints and brown coal seams, remains of former swamp forests. The granite dam in mid-river, called "Hund" or "Wolf" locally, is meant to keep the current from eroding the slope.

A walking trail begins at the Waldgasthaus Naturfreunde parking area in Duttendorf and leads through the forest down to the river gorge. The path is manageable but requires sturdy footwear and basic fitness level to navigate safely.

The cave walls preserve fossil leaf imprints and lignite seams from swamp forests, evidence of four million years of Earth history. The Salzach cut roughly 70 metres into the Flinzsand after the last ice age, leaving a steep slope riddled with caves.