User blog comment:MeDeoPal/Assassin's Creed IV Story Ideas (Ye Be Warned Of Ye Spoilers)/@comment-5413627-20121110134555/@comment-1910935-20121112190817

The vault? Because they started to drain polders. And you know, when the water's gone, you can walk there. TWCB would have hidden one of their most powerful artifacts, so it would not fall in human hands. And now we can get it.