Schönberg-Höhlensystem, Cave system in Altaussee and Ebensee, Austria

The Schönberg-Höhlensystem is a branched cave system with 35 entrances in the western Toten Gebirge, lying beneath the Schönberg (2093 m) near Bad Ischl on the border of Upper Austria and Styria. Its passages run through a block of Dachstein limestone, and the dominant southwest-to-northeast jointing gives the system the same orientation. The best-known entrance is the Feuertal-Eishöhle, reached from the Ebenseer Hochkogelhaus; behind a steep firn cone, a first hall lit by two daylight shafts leads on to the Gustave-Abel-Halle and the main system.

The cave was not scientifically documented until the 1960s, when researchers discovered its vast extent. About 40 years later, experts found that separate known cave systems in the region were connected underground.

The cave's name comes from the Schönberg (2093 m) above it, and the Raucherkarhöhle part from the Raucherkar cirque. Since 2007 the annual expedition of the Landesverein für Höhlenkunde Oberösterreich has taken place around the first week of August at the Ischler Hütte; that year's expedition found the passage linking the two systems.

The cave is not open to visitors; access is limited to researchers from the Landesverein für Höhlenkunde Oberösterreich. The best-known entrance, the Feuertal-Eishöhle, is easily reached from the Ebenseer Hochkogelhaus, but its continuation into the main system is usually sealed by ice and only opens after summer melting. The 35 entrances lie on the Raucherplateau and in the Raucherkar near Bad Ischl.

The Feuertal ice cave, one of the best-known entrances, is reached from the Ebenseer Hochkogelhaus. Inside, a steep firn cone leads into a first hall still lit by two daylight shafts; the passage onward is usually sealed by ice that melts only in summer, so explorers sometimes wait days for it to open.