After all the fat, engrossing volumes written about the awful things that happen to men at sea, from ''The Odyssey'' to ''The Bounty,'' it's a wonder people still venture into the water. Then again, there's nothing more fun than reading about what happens when they do.
Shadow Divers doesn't make the genre's top tier, but it tells an intriguing tale: In 1991, deep-sea divers discovered the wreck of a Nazi U-boat 60 miles off the New Jersey coast. Located 230 feet below the surface and filled with silt, skeletons, and swastika-stamped china, the wreck was a death trap for divers. But year after year, two men doggedly returned, trying to put a name to the rusting hulk and the bones that littered its murky chambers.
As it happens, the ocean floor is dotted with U-boats. What made this one special? Not a lot. But instead of using the U-boat as a hook to delve into the crazy subculture of wreck divers -- who eagerly expose themselves to sharks, drowning, and the bends -- author Robert Kurson struggles to set up his historical mystery. What's missing here is a strong, rounded portrait of the principal divers, whose stories seem curiously flat, cautious, and bland.