The mine is the home to various types of blood-thirsty Ghosts. These malevolent spirits (Mutineer Ghosts, Devious Ghosts, and Traitor Ghosts) will make every effort to stop any pirate. A few will actually become allies. These Traitor Ghosts must be protected from the others in order to complete the quest of El Patron.
SPOILER ALERT: (Expand to Reveal)
As part of the Raven's Cove quests, the pirate must locate several grave markers inside the mine and contact the spirits of those buried.
Pirates will also need to find journals buried by the graves.
Note: Dig spots do not show after completion of the story quest, the screenshots below show an area in which the dig spot should be located at.
Also, the following screenshots contain spoilers, if you do not wish to learn locations of dig spots for the quest, do not continue!
Below is the soundtrack played while in El Patron's Mine.