To open this trophy or accomplishment in Call of Cthulhu you must be in part 13, where you need to discover “Sarah Hawkins”. Looking for Sarah you can discover the mariner box.
In the video underneath is the accurate area of the mariner box in Call Of Cthulhu.
Journey into history
Open the mariner’s chest in the whaling station
An outline of every single existing trophy and accomplishments can be found here in our trophy manual for Call Of Cthulhu.