And this is all under the assumption that you could actually find the island by flying over it in a plane or helicopter. It's too big to just be sitting out in the middle of the ocean. an island of that MAGNitude would have been crashed into many times, would have been found by countless governments and legitimate business to be kept such a secret. It may be cloaked, which would be a clue screaming of governmental involvement, or billionaire business collaboration, but then why is everyone so suprised that a sailboat got there. If it was cloaked, you wouldn't be suprised if anything happened to 'find' the place.
Imagine the universe is a cheap tint job done on the window of a Honda Civic. Over time, bubbles appear. That's all I've got, I lost my train of thought.