Settled 2500 years, the Nan Madol site is a living memorial to the Prehistoric Micronesians that once inhabited Pohnpei. Hundred feet high basalt structures rise from the deep waters to form artificial islands serving as ritual, trade, and hierarchical centers. Deep below the surface, ancient lore proposes that underwater tunnels connect this complex and are filled with untold riches and ancient artifacts. With only canoes and crude tools, how did the Micronesians build this imposing fortress? Where did they quarry these raw materials? Do the tunnels exist as an answer to the secrets of this complex network of civilization and tradition? And can we find them?