Unlock: Liberate the Longshore View outpost.
Speak to Joseph, the wounded man inside the shack. This is a straightforward assassination mission against a group of Hoyt’s privateers, and the first target is 150 meters northwest of the quest giver. He’s firing a gun into the air for some reason, and is accompanied by two chargers and a heavy.
With him dead, proceed 400 meters north to the second target. He’s on an inflatable boat just offshore, with two normal soldiers and a sniper covering the road. It’s easy to sneak around them to the east, stab the sniper, and use a Chain Takedown to deal with the two guys in the road. After that, take out your target.
The final of the three privateers is on the small island east of the Bridge Control outpost. Your target is on the north side of the island and most of his backup is scattered across the area to the south, so you can sneak around the shuttered house, shank him, and be back in the water before any of them realize you’re there. Return to Joseph to finish the mission.