The Lurgrotte karst cave is the largest cave in the Eastern Alps of Styria, Austria. It is located about 16 km (9.9 mi) north of Graz and crosses the Tannenben karst region. The cave has two accessible entrances, one at the village of Semriach and the other at the village of Peggau. At the Semriach entrance, the sinks into the cave. At the Peggau entrance, the emerges from within the cave, flowing to the west and eventually joining the Mur River.