I am a big fan of the Oak Island story. Unfortunately, the chain of evidence was broken too many times to know these days, what exactly is, or was there. If we go back to the first story of Mcginnis, he recruited two of his friends, then 8 years later, he was part of the Onslow company(i think that's what is was called). If those stories are true, then a pattern appears that, Mcginnis was trying to get help to get the treasure(not a far stretch at all). Then, they got to 90 feet and stopped. the next day it is filled with water. If this is true, one can make the assumption, that they came back at night(Mcginnis and a few others), retrieved the treasure, and flooded the pit. The recent episode of TCOOI with the Cross from the Mcginnis sisters, would seem to make that theory true.