That's not really an island. Flygon means it just looks like an island, and if it's surrounded by water... I guess it would be. But in AC for the GameCube you go with Kapp'n in a boat to an island separate from the whole town. At that island, you have a house and a neighbor. It's also always summer there. (And you can connect with the GBA... well that's how you get the island in the first place too.)