There are a considerable variety of rebreathers available on the market today and each has their proponents. Basically a rebreather is a machine worn on the back of the diver allowing unused exhaust  gas to be reused rather than letting it be vented into the water as in open circuit diving.

Advantages

• Offer a much greater gas supply than the alternative open circuit equipment
• Supplies an optimum gas mix which gives greater decompression efficiency
• Few or no bubbles limits percolation off a cave ceiling therefore increasing visibility
• A rebreather loop delivers warm, moist gas to the diver improving thermal comfort in the water and limiting dehydration
• Gas costs are reduced

Disadvantages

• Open circuit bailout gas must be carried increasing a divers profile
• As rebreathers are complex machines they require continual vigilance, more training, higher initial financial outlay and have greater potential dangers
• Wearing a rebreather on the back limits a divers access to some Australian caves and cave passage

John Dalla-Zuanna diving a KISS rebreather in Tank Cave | Photo: Dr Richard (Harry) Harris