While there is no definitive count of all the islands in the world, as of 2014, there are 443 islands in the world with a land area of 970 square miles or greater. There are at least 335 additional islands whose land area ranges from 190 to 970 square miles.
The Caribbean islands are not one nation and do not have a capital. The many island nations that constitute the islands in the Caribbean Sea have their own capitals, such as Havana in Cuba and Santo Domingo in the Dominican Republic, which are the two largest capitals among the islands.
The Caribbean islands were formed by the collision of two tectonic plates. One plate is slipping beneath the other, which results in land being pushed up through the water. There was also volcanic activity from the collision that helped form the islands.