Once you gain control, make your way to the ships wheel and take control. After a quick tutorial on how to fire the cannons, use the Left Stick to navigate the ship and target the enemy ships. You can attack from any angle, with the new explosive barrels being dropped from the back of the ship, so navigate around until you defeat all ships for a cutscene.
Do as the game instructs and swim to the shore for a scene. After the scene, freerun across the downed tree on the left side of the path and make your way across the bridge. You should now see white beams that lead up to a path that will eventually lead to your first synchronization. Swan dive off the perch into the thickets below and pop out for a scene. Instead of following the path northwest, head to the tree overlooking the water below to the west and dive into the water far below, allowing you to collect the Treasure to the west. Check the north side of the cover for another Treasure and then head west to the Message in a Bottle, 16. The Observatoire.
To reach the area above again, use the bow of the sunken ship to make your way northeast to a Treasure nearby. Using the nearby trees, climb up and follow the path north to another Treasure before it curves west. You can skin an dead animal nearby, reintroducing the hunting system from AC III, and then get the nearby Treasure. Follow the path north and climb up for another glance at your target.
Instead of following the mysterious man, head northeast for another Treasure and then make your way up the tower for another synchronization. Dive into the water below and then head north for a scene and chase. Instead of following the man directly, look for shortcuts on the right until you catch up to the man and draw your weapons. Do as the game instructs and counter the man and then attack to defeat him.
Head to the downed tree and synchronize before you jump into the water below. Instead of heading straight, turn around and enter the waterfall for a Treasure and then head toward the schooner. After you jump into the brush you will get a tutorial on stalking zones. You can choose to either stalk your way around and lure the guards in for silent assassinations or you can outright attack them. Either way, once all the guard are defeated get the Treasure in the south and then approach the merchant for a scene.
Before following Stede, check the nearby corpse for a Treasure Map. You can now swim to the ships, take the helm, and sail out of the cape.
