When you buy a new theme park on a new island you can’t go back to the previous one, since you sold it in order to manage a better one.

Your previous rides and ingame features will be recovered in a short time, and you will be able to advance further in the game.

You have to start from scratch, but now you will have a faster flow of money thanks to higher multipliers.

You can see all the islands available and their prices by tapping on the island icon (second of the upper-right corner icons).