1. Rebreathers are scuba systems that recycle a diver’s exhaled breathing gases. What gas needs to be removed by the rebreather before the breathing gas can be inhaled again?

2. What are some well-known benefits of diving a rebreather?

3. The one-way breathing system (the ‘loop’) in a rebreather prevents the diver from inhaling carbon dioxide. What is the main component that absorbs the carbon dioxide called?

4. Closed-circuit rebreather divers only need small cylinders to provide enough breathing gases for their entire dive, commonly a volume of 3l compared to an open-circuit diver’s 11l. This is because the body does not metabolise inert gases. Which inert gases are most commonly found in scuba tanks?

5. eCCRs (electronic closed-circuit rebreathers) use computers with pre-determined set-points to maintain the partial pressure of oxygen at a set (safe) level, much like mixing the perfect nitrox mix for any given depth of the dive, but what is the biggest risk of that partial pressure being higher than 1.4PO2?

6. Rebreathers are often only associated with technical diving, but what other type of diver may benefit from rebreather training?

7. eCCRs differ from mCCRs in that mCCRs are _____.

8. In case of a problem with the rebreather, CCR divers will bring additional scuba cylinders with them so that they have back-up breathing gas/gases. What do we call those cylinders?

9. Rebreathers have oxygen cells (also called O2 sensors) to monitor oxygen levels in the breathing gas. There are usually at least two or three oxygen cells in a typical rebreather unit. How should they be stored when not in use?

10. True or False – Breathing gas inside the rebreather loop can affect the diver’s buoyancy.

11. In a rebreather course, divers are taught a skill called a ‘shut-down drill’. In this skill, what is it that the diver will be ‘shutting down’?

12. Rebreather diving is often seen as complicated, technical and difficult. What is the minimum prerequisite certification for a beginner rebreather diver course?