About 3km north of Obinitsa are the Piusa Caves. The sandstone here was excavated for over 40 years from 1922 to 1966 to supply Estonia's glass factories but now safer and faster open-cast mines are used for this. The caves have now been taken over by a large colony of bats but they do not object to occasional tourists walking around. Do bring a torch and do come as a group. There are no permanent staff on duty to deal with accidents or anyone getting lost. The caves were closed to the public in 2006 for various safety measures to be carried out.
Neil Taylor "Estonia. The Bradt Travel Guide", 2007
When leaving Värska, you can choose to visit the Piusa caves which have recently become one of the most popular tourist attraction in Põlva County. However, you should be careful when entering the caves and strictly follow the route prescribed by nature conservation officials. The caves were formed as a result of underground mining of glass sand and serve today as one of the largest hibernation places of bats in the Baltic countries. Sand was first mined here in the 1920’s and underground mining was replaced by opencast mining in the 1970’s. The layers which date back to the Devonian era (about 450 million years ago) crop out here in an especially impressive manner.