As the DM/GM, you've gotta come up with every aspect of the game world the players will explore. That can be rough. Thankfully, there's pre-made settings that you can add to your own game for a quick and easy bit of world-building. In this case, we have Draharsis, a set of three islands that are filled with mysteries. You can find this setting book up on Kickstarter now.
From the campaign:
Draharsis is an easy-to-read, easy-to-use campaign setting consisting of 3 islands waiting to be explored.
If you're looking for a 90 page campaign setting that describes every nook and cranny of the gaming world and leaves nothing to the imagination, then look somewhere else… but if you are a Gamemaster (new or experienced) looking for a resource to help serve as the backdrop of a new one-shot or campaign... then Welcome to Draharsis!
The campaign's more than 8x funded (being fair, they were asking for very little to begin with) with 18 days left to go.