When I registered they suggested I introduce myself.
I'm a long time cave diver. Got Abe Davis in 95. Trimix in 2001. Nicholson in 2003. Got my girlfriend into Trimix earlier this year and looking to do more deeper stuff soon. A rebreather seems necessary for any reasonable approach to deep diving so I'm involved in a home project to produce a couple of units that meet our needs (cost and availability being the major factors in not just buying off the shelf).
Farther back in time I used to live on a submarine 3 months at a time for 4 years. Submarines are big rebreathers for crews of 150 or so. I was a Nuclear Reactor Operator (to run the big steam plant that powered the rebreather) and also a Engineering Watch Supervisor.