Shipwreck Beach - Collectibles Near the Survivors' Camp

After using the base camp, head through the alley between the buildings. Go past the ruined building with the blue tarp roof and into the next building on the left.

Inside you'll find a document (1/4), a letter from Reyes to Roth, part of the Endurance Officers series. There's also a box of rifle/SMG ammo in the corner near the fire barrel.

Go out the same way you came in and cross the alley to the wooden door opposite. Pry it open with your axe and enter.

Inside is another document (2/4). This one is a sad little note from Jonah, part of the Endurance Crew series. Exit this room, turn right and head down to the boat.

If you're going after Achievements and Trophies, before leaving the PT boat, be sure to talk to each of the crew members. Stand close to each one and press Interact to converse until you've exhausted all the dialogue options for all three. You should see the 'TR' autosave icon at the bottom right corner of the screen as you finish each conversation. This counts toward the Chatterbox Achievement/Trophy.

Move up the slope opposite the boat onto the roof of the building where you found the first document.

Pick up the GPS cache (2/15) in the far left corner.