“The Atlantic floor was still a wilderness in Nagle’s prime, and it demanded of its explorers the same grit that the American West did of its pioneers. A single bad experience on a shipwreck could reroute all but the hardiest souls to more sensible pursuits.”

Kurson’s skillful use of imagery and rhetorical flair are on display in this quote. The fact that Nagle began deep-sea diving when it was much less commercial and more about discovery explains his promise and his later feeling of isolation. After the diving world changed, Nagle turned to alcohol as an escape.

“Deep-shipwreck diving is unusual in another respect. Because it confronts man’s most primordial instincts—to breathe; to see; to flee from danger—the layperson need not strap on the equipment in order to appreciate the peril.”

This quote points out the universal fears that deep-sea divers must confront and overcome during exploration. Diving at dangerous depths stresses the brain to the point that it can betray the body and sometimes lead to avoidable deaths.

“A good diver reveals himself in the way he gears up. He is at one with his equipment. He knows where every piece goes; every strap is the perfect length, every tool expertly placed, and everything fits.”

The text descriptively compares the actions and appearance of a seasoned diver to those of an amateur. Although seasoned divers have a much better chance of survival, and other experienced divers can spot them easily, a single misfortune can nevertheless kill them in an instant.