There are many 19th-century accounts of Oak Island, but some are conflicting and/or are not impartial. Further, physical evidence from the initial excavations is absent or has been lost. A basic summary of the history of the pit is as follows:
In 1795, 16-year-old Daniel McGinnis discovered a circular depression in a clearing on the southeastern end of the island with an adjacent tree which had a tackle block on one of its overhanging branches. McGinnis, with the help of friends excavated the depression and discovered a layer of flagstones a few feet below. On the pit walls there were visible markings from a pick. As they dug down they discovered layers of logs at about every ten feet. They abandoned the excavation at 30 feet.
About eight years after the 1795 dig, another company examined what was to become known as the "Money Pit." The Onslow Company continued the excavation down to approximately 90 feet and found layers of logs about every ten feet and layers of charcoal, putty and coconut fibre at 40, 50 and 60 feet. At 80 or 90 feet, they recovered a large stone bearing an inscription of symbols. Several researchers apparently attempted to decipher the symbols. One translated them as saying: "forty feet below, two million pounds lie buried." The pit subsequently flooded up to the 33-foot level. Bailing did not reduce the water level, and the excavation was abandoned. It was later suspected the flooding was due to a previously dug channel that was fed from the ocean, thus creating the possibilities of the pit being “trapped”.
Investors formed The Truro Company in 1849, which re-excavated the shaft back down to the 86-foot level, where it flooded again. They then drilled into the ground below the bottom of the shaft. According to the nineteenth-century account, the drill passed through a spruce platform at 98 feet, a 12-inch head space, 22 inches of what was described as "metal in pieces", 8 inches of oak, another 22 inches of metal, 4 inches of oak, another spruce layer, and finally into clay for 7 feet without striking anything else.
The next excavation attempt was made in 1861 by a new company called the Oak Island Association which resulted in the collapse of the bottom of the shaft into either a natural cavern or booby trap underneath.
The pit was left alone until 1893 when a wealthy local resident, Frederick Blair, decided to block the flow of sea water into the shaft by blowing up the channel with dynamite. He went deeper than ever before, reaching a level of one hundred and fifty-one feet. Unfortunately, all he found for his trouble was seven inches of rocks, more wood and then thirty-two inches of loose metal. He reached a level of one hundred and seventy feet, struck iron plate and then the shaft flooded again
Further excavations were made in 1866, 1893, 1909, 1931, 1935, 1936, and 1959, none of which were successful. Franklin Roosevelt was part of the Old Gold Salvage group of 1909 and kept up with news and developments for most of his life.
Excavation by the Restall family in the early 1960s ended tragically when four men died after being overcome by fumes in a shaft near the beach. In 1965, Robert Dunfield leased the island and, using a 70-ton digging crane with a clam bucket, dug out the pit area to a depth of 134 feet and width of 100 feet.
Around 1967 Triton Alliance, Ltd. and purchased most of the island. In 1971, Triton workers excavated a 235-foot shaft supported by a steel caisson to bedrock. According to Blankenship and Tobias, cameras lowered down the shaft into a cave below recorded the presence of some chests, human remains, wooden cribbing and tools; however, the images were unclear, and none of these claims have been independently confirmed. The shaft subsequently collapsed, and the excavation was again abandoned. This shaft was later successfully re-dug to 181 feet, reaching bedrock; work was halted because of lack of funds and the collapse of the partnership.