My wife and I love to go scuba diving. Have you ever tried it?
No, I'm a little afraid of breathing underwater!
I'm pretty new myself. Do you know much about how to do it! We could use some tips.
Well divers carry their own source of gas, which allows them to more with greater independance. 
Yes! It's a really fun experience. Do you know when people first started scuba diving throughout history?
Not really but it takes a lot of tech to get the high pressure gas into the cylinders and you need a regulator. 
Wow, for someone who's afraid of breathing underwater you sure know a lot about diving! Do you know what percentage of oxygen is used in the tanks?
No but I know that the volume of the gas is reduced depending on the type of system you are using.