The objects of this work are twofold: to describe the actual incidents of various interesting episodes in the modern sport of cave exploring, and to give an account of the scientific results of underground investigations in the Mendip region of Somerset. Speleology is the latest of the sporting sciences: like orology and Arctic exploration, it has two sides, sport and adventure being the lure to some, whilst others are chiefly attracted by the new light thrown by these researches on the geology, the hydrology, and the natural history of the subterranean regions explored. The chapters dealing with the scientific results are by H. E. Balch, who has been working on the geology of Mendip, more especially among the caves, for upwards of twenty years: the accounts of actual experiences, in which the sporting side is predominant, are by E. A. Baker, who described the recent exploration of the Derbyshire caves in his Moors, Crags, and Caves of the High Peak, 1903. No attempt is made to traverse the ground so perfectly covered by Professor Boyd Dawkins in his fascinating volume on Cave Hunting, and elsewhere, most of the work described here being supplementary to that done by him, and, largely, outside the scope of his aims. The authors are indebted to the kindness of the Editors of the Liverpool Courier and Daily Post, the Manchester Guardian, the Standard, the Yorkshire Post, the Irish Naturalist, and the Climbers' Club Journal for permission to use the substance of various articles which have appeared in their pages, and to M. Martel, Mr. C. Blee, and Messrs. Gough for permission to reproduce a number of excellent illustrations by them.