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?
cylinder or cylinders may be used for an equivalent dive duration. Rebreathers extend the time spent underwater compared to open circuit for the same gas consumption; they produce fewer bubbles and less noise than open circuit scuba which makes them attractive to covert military divers to avoid detection, scientific divers to avoid disturbing marine animals, and media divers to avoid bubble interference.
Scuba diving may be done recreationally or professionally in a number of applications, including scientific, military and public safety roles, but most commercial diving uses surface-supplied diving
Scuba diving
Scuba diving is a mode of underwater diving where the diver uses a self-contained underwater breathing apparatus (scuba), which is completely independent of surface supply, to breathe underwater. Scuba divers carry their own source of breathing gas, usually compressed air, allowing them greater independence and freedom of movement than surface-supplied divers, and longer underwater endurance than breath-hold divers. Although the use of compressed air is common, a new mixture called enriched air (Nitrox) has been gaining popularity due to