The story of the Oak Island Money Pit began way back in the summer of 1795, when a teenager named Daniel McGinnis saw strange lights flickering at night on an island just offshore from his home in Nova Scotia, Canada. The remote coastline is dotted with small islands, and being only a short distance from the thriving commercial center of colonial Boston, the region was known as a pirate enclave. So when he set out the next morning to investigate, McGinnis had buried loot on his mind.

When McGinnis climbed ashore on Oak Island, his curiosity only grew. There, he found a peculiar circular depression approximately 13 feet in diameter, a telltale sign that something had been buried at this spot. So, naturally, the next day he returned with the necessary equipment to begin digging.

The deeper McGinnis dug, the more curious he became; the hole definitely seemed man-made. Then, after digging down just 2 feet, he uncovered a layer of flagstone extending across the opening. There was no treasure yet, but his hunch that something valuable was buried there — for some strange or wondrous purpose — had only been heightened. He continued to dig.

At 10 feet deep, someone had again covered the hole, this time with a layer of timber — another hint of buried treasure. A second wooden layer was found at 20 feet, and a third at 30 feet. There was still no treasure, and by now McGinnis had dug as far as he could. The legend of the Oak Island Money Pit, however, had just begun.

The mystery deepens

Oak Island map Oak Island lies about 660 feet off Nova Scotia's south shore in Mahone Bay. (Map: NormanEinstein/Wikimedia Commons)

In the years since, various companies and excavation teams with dreams of buried riches have taken up the digging effort at the same spot McGinnis found, all still to no avail. Even so, the mystery has deepened. And so has the hole.

Wooden platforms every 10 feet have teased excavators, all the way down to at least 100 feet deep. At 90 feet, one of the pit's most enticing mysteries was uncovered: a stone slab with cryptic writing etched on it unlike any writing ever found before. Was it a cipher? A coded clue to the whereabouts of the hidden treasure?

The obscure tablet remained undecipherable for decades. But then, in the 1860s, the puzzle drew the interest of a renowned professor of languages from Dalhousie University in Halifax, Nova Scotia, James Leitchi, who claimed to have been able to decode the text. Its message only motivated excavators to dig ever deeper. According to Leitchi, it read: "Forty Feet Below, Two Million Pounds Are Buried."

Digging such a deep hole is not without engineering challenges; in fact, excavators have been stymied over the years by a number of issues that were only later solved with improved technology and, of course, a bigger budget. For instance, there's a constant battle against water flooding into the pit, as the hole is on a relatively small island just a short distance from the ocean. The flooding is so bothersome that some excavators have even theorized it's part of an elaborate booby trap, set up by the treasure's original buriers to foil its discovery.

The excavation has now drilled down to 190 feet — well beyond the extra 40 feet prophesied by the stone slab's inscription — but still hasn't turned up any loot. If an 18th-century treasure could have been buried at such a depth, it would have been a monumental engineering feat. And yet people still seem compelled to dig.

The effort has even drawn interest from the likes of Franklin Delano Roosevelt, 32nd president of the United States, who at the tender age of 27 decided to join the excavation effort at Oak Island. Famed actors John Wayne and Errol Flynn also got in on the action, each bidding for a chance to join the dig.

Theories abound

Ark of the Covenant Could the Ark of the Covenant — pictured here in an 1800 oil painting by American historical painter Benjamin West — have somehow ended up buried on a tiny Canadian island? (Image: Benjamin West/Wikimedia Commons)

Pirate booty remains the most popular theory about the suspected treasure, but other wacky theories have surfaced, too. Some have proposed, via various speculations, that the treasure is Marie Antoinette’s lost jewels, or that it might be secret documents identifying the true author of William Shakespeare's plays. One theory even posits the treasure might be the lost Ark of the Covenant.

Skeptics have also offered some more tempered theories, suggesting the chasm is actually part of a natural sinkhole, and that it has filled with debris over the years through flooding and via the complex movements of the water table and tides. The fact the hole appears man-made, they say, is merely an illusion created by natural processes. And of the inscribed stone slab and other uncovered artifacts? Hoaxes.

One way or another, it's worth asking: When will it stop? At what depth will it seem more like a wild goose chase than a genuine search for buried treasure? The mystery seems to have a life of its own at this point, an obsession that reaches far beyond the enticement of untold riches.

The dig has even become the subject of a History Channel reality show called "The Curse of Oak Island," which follows the efforts of the land's current owners, Marty and Rick Lagina, as they scour the island for the concealed treasure. Season 4 of the series promises to finally solve the mystery.

After more than 200 years of intense excavations, however, anything short of a bona fide treasure is unlikely to halt the hunt.