Spelunking and related activities and areas of knowledge- all of which have their fascination- are recorded here in a book that explains caves, their formation and their contents. From the Altamira prehistoric paintings, to the smallest blind salamander that inhabits caves today, the topics discussed are many and organized well enough to give a clear and cumulative understanding of the underearth. Wind , wave, lava, ice and lime caves are explained as to origin and the particular differences between each kind. Inside some famous caves- Fingal's for example and the Carlabad Caverns- we are told about stalactites, stalagmites etc., as well as about the modern troglodytes who live in southern France and Spain. Last but not least, there are cave animals and a brief account of a real spelunking expedition.