caves of barać, baraćeve špilje, croatia, sign, bat, plitvice lakes area

abyss ancient barac baraa bat bio black canyon carve carving cave cavern cavities europe exploration exploring field formation forms geological geology historic holiday hydrology karst limestone millennial mountain natural nature old palaeontology potholing rock sign site spelaeology speleological speleology spring stalactite stalagmite stone submarine subterranean symbol tourism tunnel underground valley visit welcome