You can use Idols with a blue orb to dispel fog on your Islands.

You can find the Idols in the locations you already unlocked, usually next to the territory that you want to unlock. So, if you are wondering how to unlock a certain territory, look for an Idol with a blue orb nearby.

To dispel the fog on some territories, you may need to complete a certain quest.

Keep in mind that if you buy a territory that’s hidden in the fog, the fog will not be automatically dispelled.