What is the smallest authorized scuba cylinder?

The smallest authorized scuba cylinder is 50 cubic feet (scf). Scuba cylinders are generally categorized by their volume, and the 50 scf cylinder is a common size used primarily in training environments or for very short, shallow dives. This size allows for a manageable weight and bulk that can be particularly advantageous for beginner divers who are still getting accustomed to the equipment.

While various other cylinder sizes exist, such as those holding 30 scf or larger volumes like 70 and 100 scf, these are not typically seen as the standard smallest options for authorized scuba use. The 30 scf size is less common and not widely recognized as a typical scuba tank for those engaged in regular diving activities. Therefore, the 50 scf cylinder represents a balance of capacity and usability while still being the smallest that is broadly acknowledged for scuba diving purposes.