Along the west end of the Popovo field in the Ravno district, in southeastern Bosnia and Herzegovina, located is the Vjetrenica cave, surely one of the most spectacular caves in Europe. As its name already describes, Vjetrenica is a cave through which entrance constantly blows a cold wind.This air circuit is a result of the temperature difference inside and outside of the cave. In the first half of the 20th century Vjetrenica was considered the largest cave in the Dinarian karsts.The total length of the discovered channels of the Vjetrenica is about 5.688 meters. The cave itself is filled with spacious hallways and chambers, many lakes, brooks, smaller and larger waterfalls.

The Vjetrenica has an exceptionally rich cave world with more then 100 various species from which 33 sorts were first found and described in Vjetrenica (one of these is the insect Antroherpon apfelbecki shown on the stamp). Vjetrenica is for the first time described in the first European encyclopedia Historia naturalis of Plini the senior from the year 77 n.e. Since 1950 the cave system Vjetrenica is a protected monument of nature. For tourist purposes, it was opened from 1964 up to the war in 1991. During those years inside the Vjetrenica 1800 meters of pathway was arranged from which 1050 meters was alighted.

During the war years the tourist infrastructure of Vjetrenica was completely devastated. Today, a group of enthusiasts lead by Ivo Lučić is trying to revitalize Vjetrenica and return its natural glow as a tourist attraction but at the same time and protect this natural beauty. Post in Mostar ( The Croatian post Ltd.- Bosnia and Herzegovina) has issued on 5 June 2005  a commemorative first day cover and maximum card. (Design by Dinko Raič; 1.00 BAM - 0.51 EUR; 48.28 x 29.82 mm;8 stamps + 1 vignette)