Diver with rebreather gets close to a grouper
Photo by Walt Stearns

The technical diving craze of the '90s spurred renewed interest in rebreathers, and spawned a number of new designs. For many "techies," the initial fascination with rebreathers was based on nothing more than a love for things complex and mechanical. Soon, however, divers began to realize that there were some very real advantages to rebreathers - advantages that might actually justified the additional expense and complexity of these devices.

These advantages fell into two major categories: reduced noise and decompression efficiency. Because rebreathers recirculate some or all of a diver's breathing gas, they release few or no bubbles into the water. In contrast to traditional scuba systems, which emit noisy streams of bubbles with each breath, rebreathers offer the advantage of quiet to silent operation.

Underwater photographers and fish watchers discovered that by switching to rebreathers, they could come within inches of typically shy species, allowing them to observe, document and photograph the underwater environment in a more natural state.

The other major advantage of rebreathers - decompression efficiency - stems from these devices ability to deliver the optimum gas mixture for a given depth. The more simplistic type of rebreather, usually referred to as a semi-closed system, will a blend of nitrox or mixed-gases that can be custom-blended for the intended depth of the dive. The more complex fully-closed rebreather systems, which are often computer controlled, can actually change the gas mixture based on depth and the nature of the dive.

These characteristics allow divers with appropriate training to extend their bottom time or to shorten decompression obligations when engaged in extended range diving.

One additional advantage of rebreathers that most all users appreciate is comfort. Instead of the ultra-dry, cool air delivered by a conventional scuba regulator, a rebreather delivers warm, moist breathing gas. Many divers feel that this keeps them warmer during a dive, and helps prevent dehydration.

Rebreathers are an advanced and often complex type of scuba, and should be used only by those with appropriate training and experience.