We hear this question all the time. Can a small Spare Air tank actually help you get to the surface in an emergency? The answer is yes, and the reason is physics. At depth, air is compressed. If you stayed deep, a small tank would not last long. But in an emergency, you are ascending immediately. As you move toward the surface, pressure decreases and the air in the tank expands. That expanding air gives you enough breathing time to reach the surface when Spare Air is used as intended. It is desi