A manual that combines education and theoretical research with practical activity, a result of the experience of Umberto Pelizzari, one of the major protagonists in the history of freediving (16 world records et the first man to break the wall of 150 meters in depth). A complete text, which accompanies the freediver into the discovery of a fascinating sport and discipline with extraordinary mental components. With its previous editions, "Manual of Freediving" has been the most widely distributed freediving manual in the world, translated into eight languages, selling more than 30,000 copies in Italy. In this "Manual of Freediving, underwater on a single breath", each chapter has been completely re-written and enriched with the most important innovations and knowledge that in the recent years have contributed to improving and making the practice of freediving even safer and more enjoyable. The chapter on relaxation and mental training represents one of the greatest insights into the application of mental strength in freediving. Developed in a very simple and practical way, it contains various "guides" for the autogenic training sessions and mental training. From basic to advanced level, topics such as the following, are dealt with simplicity and many practical references: breathing (the correct use of the diaphragm, respiratory sensitivity and effectiveness, abdominal and thoracic breathing, chest mobilization, etc.), equalization (all manoeuvres are described and trained with the latest educational protocols, dry and in water), physical and specific training, monofin, safety in the water, etc. According to the most modern freediving teaching methods, over 400 pages of text and illustrated exercises with useful images will allow students and their instructors to build a straight forward and effective didactic path.