There is an island in the North Atlantic...
I've been following this story since I was a kid, so are the two brothers out digging for treasure.
Story goes, in 1795, some kids saw a mysterious light on a nearby island in Nova Scotia. They took a boat out and found a pulley hanging from a tree branch over an odd depression in the ground.
Like any ingenous kids, they went "Yay! Pirate treasure!" and started digging.
10 feet down, they hit a floor of oak logs. They pulled those out and kept digging. They found another floor every 10 feet until they hit 90 feet, which had a mysterious carved stone on it.
After that, their hole flooded and people have been digging for treasure ever since. To a point where the island has been so thoroughly dug up, the location of the original "money pit" has been lost for decades.
The History Channel show has been trying for 12 seasons now. Lots of myths and legends about it.
The mysterious "90 foot stone" has been lost, no rubbings or photographs were made. A transcription and translation popped up, but it doesn't seem to be older than the 1940s.
In the 1960s, several people died during the excavation, the show is fond of repeating the "curse" that 6 people have died, and a 7th must die before the treasure can be recovered. There is no reference to that curse prior to the 1960s or 1970s.
By the earliest accounts, McGinness (and the original "kids") gave up after digging 30 feet. It wasn't until the Onslow group that they excavated down to 90 feet.
I would accept that the original pit was a natural sinkhole except for the coconut fiber evidence. As we all know, palm trees don't grow in that region. Coconut fiber, called coir, was a common trade item because it was used like hemp. Common applications were rope, mattress stuffing, and matting. It can also be mixed with pitch to make a substitute for oakum - a common material used to waterproof ships hulls.