With The Sharks

A few weeks ago, we went on an underwater expedition using Google Expedition and some Virtual Reality goggles. We went underwater. 

"Why are people walking with the sharks?". 

There are books for that. It may have been 3 weeks later, but that boy's question needs to be honored. So we began reading about the sport that is Scuba Diving. 

"How does oxygen go into there?"

 I'm sure there's a book for that too...