After reading Neil Swidey's engrossing Trapped Under the Sea (Crown), you will never look at a bridge or tunnel the same way. In captivating detail, the book explores the little-known world of commercial divers – construction men who can work underwater daily for weeks at a time and are 40 times more likely to be killed on the job than the average worker. Swidey chronicles one of the worst disasters in the profession's history: a 1999 incident in which five men were sent 250 feet below the Boston Harbor seafloor to work on a 10-mile tunnel and only three returned. Even by commercial diving's extreme standards, the job was unusual – the tunnel was dry, pitch-black, and completely deprived of oxygen. The crew traveled through it in a pair of customized Humvees before the space got too narrow and they had to drag their gear on foot, all while breathing through an apparatus only slightly more sophisticated than a garden hose. If something went wrong, no rescue crew could descend in time to save the men – they were traveling nearly three miles farther in length than the deepest ocean point on Earth, the Pacific Ocean's 6.8-mile-deep Mariana Trench. As Swidey writes, the divers were being "sent into the darkness with an improvised, untested plan. . . . They might as well have been working on the surface of the moon."

Trapped Under the Sea hits its stride in the detailed portraits of the five divers – itinerant blue-collar workers who began commercial diving for the thrills and the money (their minimum day rate was $742). The crew includes DJ, a 29-year-old Boston native attracted to the job's military-special-ops feel; Billy, a top mechanic who shows up with a Tupperware of fresh roadkill; and Riggs, a former Navy man who suffers from claustrophobia and has to use a series of mental tricks to keep his affliction at bay. "[The divers] were used to danger," Swidey writes about the unsung men risking their lives to build tunnels and highways across the country. "They were Navy SEAL–type guys who run toward it when everybody else is running away."