High-pressure cylinders are relatively small, yet very strong containers that hold large volumes of compressed gas. Being able to carry your gas supply with you is what defines SCUBA (self contained underwater breathing apparatus). Whether it’s filled with regular filtered air or enriched air nitrox (higher oxygen and lower nitrogen content) or trimix (three-gas combination) for technical diving, a scuba tank is one of the most important pieces of gear. Visit your PADI Dive Center or Resort to get advice about tanks.
Whether you own one tank, multiple cylinders or none depends on your dive activities and location. To select the right cylinder for you, think about size and capacity.