Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Single Rope Technique (SRT) is a set of methods used to descend and ascend on the same single rope. SRT is used in caving, potholing, rock climbing, canyoning, roped access for building maintenance and by arborists for tree climbing. In the 1930s, as caving became increasingly popular in France, several clubs in the Alps made vertical cave exploration an outdoor sport. During WWII, such a team composed of Pierre Chevalier, Fernand Petzl, Charles Petit-Didier and others explored the Dent de Crolles cave system near Grenoble, France which became the deepest explored cave in the world (-658m) at that time. The lack of available equipment during the war forced Pierre Chevalier and the rest of the team to develop their own equipment, leading to technical innovation.