Niihau, the 7th largest island of Hawaii is completely privately owned by one family who seeks to maintain it as it was purchased in 1864 for $10,000 in gold, including the native population.
There is an island in the Scottish Hebrides that is owned entirely by its people. With a population of 83, the Isle of Eigg has been owned by its community since being bought in 1997, after decades of issues with absentee landlords, and generates 100% of its electricity using renewable energy.
There is an island known as “Just Room Enough Island” that has just enough room for a tree and a house.
Pheasent Island is jointly owned by France and Spain, for six months alternatingly.
There’s a random island off of the east coast of Canada called Random Island.
Hans Island is a disputed territory between Canada and Denmark. When the Danish visit, they leave a bottle of Schnapps for the Canadians. When the Canadians visit, they leave a bottle of Canadian Club for the Danish.
There is an underwater island that Sicilian divers have planted a flag in for when it breaches the surface.
Unclaimed dead in NYC are buried in a mass grave on an island run by the Dept. of Corrections and staffed by convicts; Over 50,000 bodies are buried there and the press isn’t allowed to enter.
There is an island near Italy that was the site of wars, a dumping ground for plague victims and an insane asylum. It’s considered so dangerously haunted that the Italian government does not allow public access.