Quick calculation for folks. If sea levels have risen even 1mm per year for the past six hundred years, then we are dealing with about two and a half feet of land around Oak Island that is now underwater, but once wasn't. An average 2mm rise would double that number. Wouldn't someone want to take rising sea levels into account with regard to Smith's Cove? If a person believes the beach at Smith's Cove to be artificial, then those simple figures above would make the idea plausible.
Just some things to ponder, that's all.
I looked into this hypothesis years ago and found that many of the buildings in venice date back to this time period and there has been no appreciable rise in ocean water. There have been "some" building where it was noted they where sinking but not overall.