According to legend, seven searchers must die before the treasure would be found. Up until the show, six had died, leaving one more to die.
Since the show has started, three people directly connected to the treasure hunt have died:
1) Matt Chisholm. (Died while attempting to retrieve an old Masonic map of the island)
2) Craig Tester's son, Drake Begley. (Died in 2017 of a seizure disorder)
3) Dan Blankenship. (2019)
Drake died of medical issues, and Dan died of old age.
Matt's death is the only one clouded in mystery. Very little information is available about the circumstances surrounding his death.
Matt Chisholm had rare and aggressive form of stage IV Lung cancer. He died in his childhood home.
The curse is about a person dying in the act of the search, like digging a tunnel.
Some of the six that died were because of poisonous gas which also lends to the leaving documents in mercury to preserve them theory. High levels of mercury have been corroborated on the island. The levels of mercury should not exist in that area. They corroborated this when they excavated the blue clay pit in the eye of the swamp.