There was a phantom island off the coast of Ireland called Hy-Brasil, which was not discounted until 1865, seven years before its last sighting.
Hy-Brasil was known about for hundreds of years, yet for almost 150 years it’s been known not to exist. Maps from 1623 clearly depict the island as well as several others that were all later proved not to exist. These are what are called “phantom islands.” Like many of these phantom islands, Hy-Brasil was based on a combination of legend, faulty observation, and wishful thinking.
Its earliest appearance on a map dates from 1325. In 1497, a Spanish diplomat reported to have made a journey to the island, the first known of many who claimed to see it. Another of these was John Nisbet, a captain who in 1674 claimed to have anchored on the island and sent four men ashore. They allegedly met an Irish monk who gave them gold and silver.
For years, it was rumored to be obscured by mist except for one day every seven years. Other captains also visited the island and confirmed what Nisbet said. The last appearance of the island was in 1872, seven years after it was officially removed from nautical charts. TJ Westropp, who had twice seen the island, brought a party of witnesses to see the island with him. They all claimed to see the island appear, and then disappear forever. What do you make of all of this?