Destiny Islands is Sora's homeland.
There are two main islands - The one in this image, along with a smaller one, and another one that's more 'advanced',
and looks like a normal town, with houses and a school.
Sora is only actally seen on the former, as this is where he lives, and where he plays with all his friends.
This is also where his adventure began, and where it ended as well.
In the first Chain of Memories games, you cannot see the other island at all.