The Aldranser Bach is a small stream near Innsbruck, Austria. It has its source near Aldrans amidst the forest and flows in northern direction to Castle Ambras. Above the castle were a swimming pool for the public which was formerly fed by the Aldranserbach. In the big garden of the Castle the brook supplies the Great Pond with fresh water and then flows further through the Forest Park to Ambras, where it merges with the Lanser Bach and then further into the Inn River.