This textbook is ideal for all recreational divers who have discovered the joy of their hobby and want to get more involved in the sport. It covers all the theory required for Advanced Open Water Diver and/or 2-star diver certification. It also includes some practical examples in the form of short film clips that can be accessed online via QR codes. This book does not overload you with unnecessary knowledge, but leads you directly to an internationally recognised diving certification for advanced recreational divers. The book also includes the two speciality courses in underwater navigation and group leadership, which are required by most of the CMAS and R.S.T.C diving associations.