This book focuses on Romania's more than 12,000 caves, which developed in limestone (including thermal water caves), salt, gypsum, and occasionally in sandstone. It examines these caves and related topics in a format suitable for cavers, while also addressing a broad range of aspects useful for students and researchers. Since the Institute of Speleology was first established by Emil Racovita in 1920, a great deal of research has been conducted on all cave and karst types. As such, the book examines a variety of scientific fields, including karst geology, hydrogeology, biospeleology, paleoclimatology, mineralogy and archaeology.