How and why Oak Island's treasure pit and complex flood tunnel system work to protect the buried treasure -- even from today's treasure hunters Oak Island and its mysterious underground shafts and tunnels continue to fascinate. Treasure hunters are undaunted -- but come up with little or nothing. Experienced mining engineers Graham Harris and Les MacPhie spent a decade investigating the enigma of Nova Scotia's Oak Island. They have linked the design of the original money pit and the complex flood tunnel system protecting it to mining techniques practiced in Europe in the seventeenth and eighteenth centuries. The deep mine shaft where the treasure lies was later protected when the flood tunnel system was constructed to link the shaft to the ocean. They explain how the tunnel system has worked to ensure that what lies beneath Oak Island is safe -- even from treasure hunters armed with the latest equipment and technology.