Lokrum is a green island, covered in fertile land and lush flora. However, what lies underneath that thin layer is clearly visible only at the shore: the whole island is made of thick layers of sedimentary rock – limestone and dolomite.The sedimentary rocks hide an interesting geological story millions of years old – they used to be a part of the Adriatic-Dinaridic carbonate platform. The platform’s remains still make up the karst region in Croatia, from Karlovac, Gorski Kotar and Lika to Istria, the Croatian Littoral and Dalmatia, but its largest part has sunk under the Adriatic Sea.