The mystery of Oak Island on the Atlantic coast of Nova Scotia presents an engineering riddle on par with that of the Easter Island stone heads. In 1795 a boy saw a curious hole by an oak tree, where the earth had sunk. He brought back two young friends and they began digging. Two feet down they found a layer of carefully laid flagstones about thirteen feet across. Clearing the flagstone, they dug down ten feet and came to an oak platform; ten feet below that they found another oak platform, and ten feet below that another still. Later digging revealed that these platforms continued down until at 90 feet a huge stone was uncovered with weird symbols or code chiseled onto it. Well, the digging has been going on for 200 years, with over two million dollars spent and 31 shafts dug--some over 200 feet deep. A fantastic underground network of manmade tunnels has been revealed, as well as an extremely sophisticated set of water traps, plus a hundred-foot artificial beach made of tons of coconut fiber. (This fiber is highly resistant to water damage and was found in the original shaft also--but there are no coconut trees within 1500 miles of Nova Scotia.) Fabulous explanations include Vikings, Incas, pirates, French royalists concealing the Crown Jewels, even the Bacon-Shakespeare mss. O'Connor, a Wall Street Journal reporter, makes a good stab at an answer--but the final one hasn't been dug up. Staggering.