In traditional open circuit SCUBA, you exhale bubbles. Those bubbles contain extra carbon dioxide, nitrogen, and non-used oxygen. A closed circuit rebreather eliminates the bubbles of used gases and recycles the unused gas back into the system. It then adds oxygen from a separate tank to replace any oxygen your body used. The goal is help you reduce and refresh the amount of air you need through recycling.
Rebreathers have many advantages over typical open circuit SCUBA set-ups. The biggest advantage is that no gas is wasted. Typically, a diver uses about 75% of the oxygen in a breathe of air and wastes 25%. The rebreather reuses that wasted 25%, which makes your air tank more efficient. In addition, when a diver is using air mixes that use expensive gases like helium, the recycling of the gases makes diving more cost efficient.
Because of the “closed” circuit, rebreathers do not create bubbles, so they are less noisy. This a real advantage for scientific divers because they do not disturb marine life when they approach and can get much closer to creatures without alarming them. Air from rebreathers is also are easier to breath because the gases are warm. Plus, rebreathers can adjust the ratio of gases in the tank to reduce the time of lengthy decompression stops.
Rebreathers have been shown to actually be safer on deeper dives over 75 meters or in overhead dive spots like caves or wrecks or ice because you use your air more efficiently. These are situations that scientific divers often find themselves in.
While rebreathers have plenty of advantages, they are also risky. Hypoxia and oxygen toxicity are common even with the most competent divers. Divers need to take rebreather training and stay current on the latest technology if they want to utilize the benefits of rebreathers in their diving.
Rebreathers are a fantastic option for scientific divers. They allow divers to approach marine life and observe the fine details of habitats, plants, and creatures without causing stress to the organism. They are safer in situations such as polar ice diving, cave diving, or deep diving because the amount of air you carry will last you longer with a rebreather than with a standard open circuit SCUBA system. Rebreathers efficiently recycle the gases to allow more available air for divers. With the proper training, they can bring scientific diving to a new level.
