To unlock this trophy or achievement in Call of Cthulhu you have to be in chapter 13, where you have to find “Sarah Hawkins“. In search of Sarah you can find the sailor box.
In the video below is the exact location of the sailor box in Call Of Cthulhu.
Voyage into history
Open the sailor’s chest in the whaling station
An overview of all existing trophies and achievements can be found here in our trophy guide to Call Of Cthulhu.