I read as a Kid the same stories that Rick and Marty read and was fascinated with the possibilities on Oak Island. I hope that they can uncover the truth and put this mystery to rest.
With that said here is my take on the Oak Island mystery;
1: pirates were not known for burying their plunder, but dividing up their cut and spending it. Some may have used their share to increase their social standing but to bury it so deep as to limit their ability to recover it is not very likely. I only know of a couple instances where some amount of the valuables were buried. One was teach leaving a payoff to the Virginia Governor and the other was contributed to Captain Kidd.
2: Be it an English or Spanish military vessel may have captured or recovered a valuable shipment and decided to stash the valuables on an uninhabited island and continue on the official mission planning to return at a later date to retrieve the goods. Again burying it more than several meters would be time consuming and unnecessary.
3: Fool’s gold being mined from the island. Let’s look at it from a time line, first a ship stop on an island for some reason and finds pyrite, so what next start a full scale mining operation or continue picking up the visible pyrite for the beach area while finishing up doing what made them stop on that island in the first place. I believe the report said the ship returned to England with 2500 lbs. of fool’s gold, but it does not state if that amount was ore or pure Pyrite. It does not take that much ore to make 2500 lbs. Now what are the chances the ship’s crew were experience miners that could possible construct tunnels under Oak Island, then follow ore veins through the solid rock and process the ore to extract the pure pyrite. By the way you have to crush the ore then smelt it. This would have showed them that it was in fact not gold at that point. I find this even more highly unlikely due the lack of any visible mining shafts on the island. Another thing is that the size of the island is very small and given the natural ground water depth the odds of having man made tunnels below about 60 feet is astronomical. Fool’s gold does run in veins similar to gold but the likely hood of a vein running vertical for more than a few meters just does not happen in nature. Also the time it would take to tunnel through solid rock following the veins would take several years to complete. This would have given the British ship more than enough time to return to England and find out it was not gold they were transporting thus stopping the operation.
4: the voids or caverns at 230 feet. These could be natural formations, part of the aqua filter running under the island. I have heard nature does not make square lines but I disagree. I have been in caves with underwater lakes and rivers. Nature makes every shape you can imagine. For example natural crystals have very straight lines, and some crystals grow 60 feet in length. Rare yes but it does happen.
If the stories are true about the pit and the timbers every ten feet then someone did do something there. Not in the past people of different societies created some very amazing things that we would have a hard time duplicating with the equipment we have today. However most of the great wonders they built was to show not to hide for public view.
So where does that leave us, Masons, Templar's, Phoenicians, Vikings, Native Americans, gophers, Aliens?
