Hypothetical: someone is looking at a satellite photo of the pacific ocean, and they see a reasonably sized (say, about as big as the big island of Hawaii) island that, somehow, no one has noticed until now. It’s way out in the middle of nowhere, far far from any country’s territorial waters.
What happens? There’s a common image left over from the age of exploration of someone planting a national flag and saying “I claim this for Spain”, but did that ever have any recognized meaning in whatever the international law of the day was? Would there be a race to get a ship or helicopter or parachutist out there as soon as possible to “claim” it? Would the nationality of whoever spotted it on the map be relevant?
Suppose there are people living on this island. What happens then, both from a legal and practical standpoint? Presumably there would be a lot of fascination and camera crews would want to go film documentaries and so forth. Who would they talk to to get permission? If this island wasn’t part of any recognized country would it be in any way illegal to just charter a plane, fly there, land, and start interviewing? If not, what organization would have the authority to stop you from doing so? One might hope that there would be some sort of attempt at communication-without-interference (not to mention not giving them all Malaria). Is there some organization with expertise in doing things like that? Where would they get the authority to actually attempt it?