This achievement is earned for finding optional photo #10. If missed on the first run, you can "Play Episodes" and select specific parts of the Episode in order to find the missing optional photos through collectibles mode
. The following collectible is described and can be seen below:
] - Optional Photo #10
As you approach Chloe on the bench near the lighthouse, stand behind her in order to see the prompt to take a photo of the sunset.
Collecting all 10 photos will also reward you with the following achievement: