Trimix - a mixture of oxygen, helium and nitrogen - allows a diver to experience less narcosis during a dive than when breathing air or nitrox. Previously the exclusive preserve of deep divers, trimix is experiencing a renaissance - with divers in the 24 - 40m range coming to appreciate the benefits of a clear head underwater. This book explains the techniques, tips and equipment needed to safely dive with Trimix. It's the ideal companion for the IANTD Recreational Trimix Diver or IANTD Advanced Recreational Trimix Diver courses, but can also be read alone.