The speleological society “Zelena brda” was founded in 1972 to study karst and karst phenomena (pits, caves, estavela, sinkholes…) We also work to popularize a healthy life, life in and with nature, and to protect the natural environment. One of the activities is to familiarize local residents and tourists with the cave world of Trebinje and Herzegovina. We organize tours for groups of up to 10 people.