My wife and I love to go scuba diving. We usually use a rebreather too so we can extend the time underwater
My wife and I do as well, we really enjoy diving in Hawaii.  Where have you gone diving before?
We've been cave diving in some water-filled caves in Costa Rica!
Cave diving seems especially risky, I bet it's quite thrilling!
Yeah.. it's an extreme sport because it can be dangerous. It' commonly done for scientific reason too because it's a whole new world.
It really is, there's a lot to be learned from cave diving.  New species, cave drawings, ancient burial sites and more.  Pretty great stuff.
Yes. We're both actually members of the NACD. Its an organization that offered training courses for cave diving. 
Cool!  How long did it take to receive certification?