https://www.belfastentries.com/stories/myths-legends/hy-brasil
The mythical_island trope certainly has its own mystique.
https://www.irishcentral.com/roots/history/hy-brasil-irelands-disappearing-island
https://mythicalireland.com/blogs/myths-legends/the-phantom-island-of-hy-brasil-in-irish-myth-fable