Participate in a challenge or free play session at each location on Villeria, which is the northern-most island that you start on. Unlock conditions for each location are listed below:
WIP - PLEASE PROVIDE FEEDBACK ON VALUES. THANKS.
Docks (Level 4, 450 Gold)
Residential (Level 8, 6000 Gold)
Fairgrounds (Level 12, 12,000 Gold)
Basketball Court (Level 14, 60 Gems)
Rooftop (Level 28, 300 Gems)
Unlocking everything on the island would require 360 Gems. If you can stockpile this amount, upload your save to the cloud and unlock all areas on the island. Participate in a challenge or free play session at each location to unlock the achievement, and then re-download your save from the cloud to recover your spent Gold and Gems. (UNCONFIRMED - thanks I am JeffRay90 for the values and quick solution idea. Please let me know if this works for you in the solution comments).