Freediving is diving without a breathing apparatus. In many languages, freediving is referred to as apnea(breath-holding) or apnea diving. Freediving was still a relatively unknown sport around the turn of the millennium, but as organized freediving has increased, knowledge of the sport has also grown rapidly. At the same time, certain risks associated with the sport have been recognized. However, when performed correctly, freediving is safe and rewarding. Spreading correct information and promoting safe practices among the general public has become an important point of focus for the core group in the freediving community. Unlike scuba diving, freediving is something almost anyone can take up. All that is needed is some basic equipment and a place to dive. Some may feel that freediving is easy and that taking lessons is unnecessary. While leisurely snorkeling is usually quite safe and easy, adding the elements of increased performance and evaluation into the mix will inevitably introduce some risks. Adequate knowledge combined with good skills helps in controlling these risks. This book is intended to be a basic guide to freediving. Even the experienced diver will find new perspectives and good tips in this book, while the beginner will gain a solid understanding of the basics. Our effort has been to present matters in a neutral, intelligible and personal way, and it is our hope that the practice of safe freediving will spread far and wide.