Levels are added every 2 weeks, check the Overworld for updates.
Level 1 - https://www.fortnite.com/creative/island-codes/6163-6895-6715
Level 2 - https://www.fortnite.com/creative/island-codes/5085-5164-1180
Level 3 - https://www.fortnite.com/creative/island-codes/4460-1710-9470
Level 4 - https://www.fortnite.com/creative/island-codes/7178-8056-6169
Level 5 - https://www.fortnite.com/creative/island-codes/2575-9924-4566
Phobos Overworld - https://www.fortnite.com/creative/island-codes/1662-4636-2902