Closed Circuit Rebreathers

In contrast to conventional scuba or open circuit where most of the breathing gas is wasted on exhalation into the surrounding water, APD rebreathers are all fully closed circuit systems in which all of the exhaled breath is retained within a closed loop.

It is then filtered and refreshed and recycled back to the diver for further use, giving the ultimate endurance of any breathing apparatus.

Only during ascent and mask clearing are bubbles emitted.