Answer to Question 1
I, as author, was very taken with Ehrenfeld's ideas. Your students will have other
answers. There are many economic and ecological justifications, and they are important.
For some people, they are the only important arguments.
Answer to Question 2
This is correct. People who dive too deep can be crushed, and many people have
heard of the bends, an affliction caused by the release of nitrogen bubbles into the blood as
the increased pressure is reduced by a rising diver.