"Ribino" is an area of 66.3 ha..As proposed by The Bulgarian Society for Protection of Birds, it was declared a protected area.It aims at protecting rare plants and animals as well as karst landscape that includes rocks, springs and caves.
The soft, yielding, calcareous terrain has shaped a beautiful canyon with a characteristic landscape. The region abounds in caves with a total length of 600 metres, which are mapped and documented in the Bulgarian Speleology Federation. There are many archeological finds that have left evidence of cave-dwelling communities in the distant past. The "Samara" cave (one of the longest in the Eastern Rhodopes) and the "Mirror" cave were included in the list of 250 most famous caves in Bulgaria.
The cave fauna is unique. New invertebrate species of the Niphargus, Roncus and Balcanopelatum genera have been found here. The wood louse Trichoniscus rhodopiense , which is a Bulgarian endemic, lives here along with the Balkanodiscus frivaldkyanus snail, which is also a Balkan endemic.
The caves are home to 10 species of bats, 7 of which are included in the World Red List. There are a number of other protected species.