Find Sam and talk to him to learn about your next mission. Next, grab a vehicle and head to the marked location. Once you've entered the area, stay undetected and head to the cenote. You may want to scout ahead and use your camera to tag enemies. You can't kill anyone for now so move close and lure him away by throwing a stone.
Follow the platform and hide behind a cover before entering the cave. There's another enemy there. Lure him away or wait for him to leave then continue inside. Remain crouched all the time and move behind cover to ensure that you're undetected. In the first cavern with two guards, you can circle around and hug the walls to the right.
Once you've reached the second cavern leading to the dock entrance, there'll be one guard that will blocking your path. Fall back to the cavern and climb up the upper ledge. Now throw a rock near the guard to get his attention, then keep luring him out of the way. Once he's out, quickly head outside and follow the ramps leading to another cave.
Inside that cave lies two more enemies. Wait a bit and they'll change positions. Once clear, follow the walls to the left to circle around them safely. However, there are more enemies ahead, including two heavies. Just move quietly under the ramp to the right.
Don't exit immediately as one the guards guarding the ramp above you can see you. What you can do is to throw a rock towards his direction so he turns around then quickly throw another rock to the opposite direction to lure the heavies' attention away from the cave exit. Crawl out and quickly take cover behind the metal plate. Once clear, dive to the water and swim to Hoyt's ship.
Climb up the ship and kill the recruit to get his uniform. After calling Sam, move ahead to have your ID scanned. After the conversation, go to the stage for an orientation. You can now swim towards the boat but if you want, you can use this chance to open the lootboxes around the area. Once done, exit the cave to complete the mission. After that, you can also use the privateer's camps as fast travel stations.