SCUBA Diving

SCUBA stands for Self Contained Underwater Breathing Apparatus (SCUBA).
You have two options for scuba diving. Open circuit or Rebreather sets.
For Open circuit system you can use scuba set, diving cylinders containing breathing gas at high pressure.
For Rebreather sets or AKA Closed-circuit breathing system. This will allow you to recycle what you exhaled that will reduce the volume of gas use thus making rebreather lighter compare to open circuit. It was initialy design for covert operations for military but later used for scientific and media divers.
The alternative for the open/close circuit system circuit would be using air compressor on the surface paired w/ umbilical. It could be with diving helmets, full face diving masks or connected to the mouthpiece with a regulator. But there are groups in the Philippines that use air compressor with umbilical only to supply air without mouthpiece! They are called Mananahong. They dive to get tahong or saltwater mussel.