The concept of the rebound point in technical diving and how it is calculated accurately to ensure a safe return.
The rebound point is a life-saving decision in technical and cave diving.
The point at which the return must begin before the air runs out. It is calculated by dividing the air into thirds: one third for going, one third for returning, and one third for emergencies.
Going back is always harder than going. Fatigue and emergencies consume more air than you expect.
A diver who calculates his rebound point accurately is not surprised by running out of air.