Shipwreck Beach - Area Northeast of the Survivors' Camp

Now head northeast, away from the campsite. Don't worry about Alex. He won't be any worse off if you take a little time to explore.

Ahead on the left is a tall rock formation with a salvage crate sitting on a ledge. On the right is the entrance to a Challenge Tomb. It won't open yet, so ignore it for now. Look to the east to spot another mine (5/10) that you can explode for the Challenge. Lying next to it on the sand is a GPS cache (4/15).

Grab the GPS cache and then climb onto the rock ledge and crack open the salvage crate. Then follow the sandy path up the slope between the large rock formation and the cliff.

Climb onto the ledge on the left, head back along the ledge to the south.

jump across the gap to find a food cache. Then continue along the ledge and around to the right.

Climb onto the ledge ahead to find another cairn (3/5) to dismantle for the Cairn Raider challenge.

Then climb back to the ground and head down the beach toward the shoreline.

You probably noticed this before, but there are wild boars, seagulls and crabs throughout this area that you can hunt for XP and salvage. Now is a good time to do a little hunting. Killing seagulls helps with the Feather Duster Achievement/Trophy, in case you haven't unlocked that one yet. Shooting one of the crabs also unlocks the Crab Cakes Achievement/Trophy. As far as I know, it doesn't matter which crab you shoot. The one circled in the screenshot above was always my FeeFee.

Climb the wooden stairs into the ruined building near the shoreline. Inside on the right is a salvage net.

On the left are some arrows. After picking up the arrows, drop down through the hole in the pier to find another GPS cache (5/15).

If you missed the 4th mine when you returned from the galleon earlier, it's half buried in the sand off to the right. Blow it up for the Mine Sweeper Challenge.