When 1 tank is not enough
(referred to as tec diving or tech diving) is scuba diving that exceeds the normal agency-specified limits of recreational diving for non-professional purposes. Technical diving will most certainly expose the diver to hazards beyond those normally associated and accepted with recreational diving, and to a greater risk of serious injury or in exceptional circumstances death.
These risks may be reduced with the appropriate skills, knowledge and experience, also by using suitable equipment and procedures for that level of diving. The skills may be developed through appropriate specialised training and experience. The equipment often involves breathing gases other than air or standard nitrox mixtures, and multiple gas sources