Corsica was added in the 1.36 update and requires the Vive la France ! DLC. The island can only be accessed from the French or Italian coast (the second option is only available to those owning the Italia DLC too).
This achievement requires the player to discover all cities on the island of Corsica. There are 6 cities in total on the island and all cities must be entered/being near them until the name of the city turns from grey to yellow on the map.
The cities required are:
- Ajaccio
- Bastia
- Bonifacio
- Calvi
- L'Île-Rousse
- Porto-Vecchio
When all 6 cities are discovered, the achievement should unlock.