I used to live on Belle Island. It’s part of the Venetian Causeway, which is a chain of islands in Miami Beach. It’s a little island, but feels part of the whole South Beach area. You can see an old arias view of it on the Wikipedia page to understand how little it is. https://en.m.wikipedia.org/wiki/Belle_Isle_(Miami_Beach) You can walk and drive to it though, because of bridges, so I’m not sure you count it as an island for this Q. I loved the visual of all the water around, and it felt a little separate, and special, even though it was part of the greater South Beach area. Sometimes I wish I still owned my condo there.
I’ve vacationed in St. Thomas and St. John island in the USVI. It was a long time ago. At the time I lived in a cold climate, so being on a tropical island felt warm and like vacation and I guess a little foreign, even though it was/is the US. At the time it didn’t feel like a place I could live. Meaning, I’m amazed anyone got to live on an island like that. Now, that I’ve lived in Florida, I don’t feel that way anymore. It is possible to live where it feels like vacation. Restaurants were expensive. Having to import a lot of the food made the prices especially high I guess.
Also, I’ve been to Puerto Rico and the Dominican Republic. I’ve been to Japan also since you mention it.
Puerto Rico I remember one time staying at the Intercontinental hotel and my room facing the ocean. It was really fabulous. Perfect weather and the waves rolling in. I ate at the hotel restaurant outside right next to the water. I was there for work that time, so during the day I was inside of the mall mostly, getting my job done.
Dom Rep I was staying with my SIL in Santo Domingo. She lived in a medium-rise building. I remember the generator for the building kicking on almost every day, because the electricity would go out. The traffic was ridiculous. Traffic lights not making sense. You could easily see the poverty around with 3 people piled on a moped, and old cars full of people. We drove out to Casa de Campo one day, and then you really saw the extremes of poverty right next to wealth.
Japan didn’t feel overwhelmingly like an island. Probably, mostly, because I was in large cities like Tokyo and Kyoto, and the size of the island to begin with. Japan, the most prominent thought in terms of what could go wrong was earthquake, while on all the other islands I mentioned it was a Hurricane. Not that I walked around worrying about those things, but it crossed my mind either because of a mention of a previous earthquake while in Japan, or a mention of a storm on a tropical island.
I’ve stayed on Manhattan island, NY many many times, but I guess that doesn’t count. Most people don’t think of NYC as an island, even though it is.
Maybe the only islands that count are those that are island nations?
Whenever I stay by the ocean I feel like it’s amazing how the land ends. One time I told that to a friend of mine who lived on the beach, on the Atlantic, and he said that it was interesting I said that, because he always feels it’s amazing how the water keeps coming in. He meant the waves coming to shore.