Optional Missions:
- Stay out of combat
- Air assassinate Du Casse
Grab the rope and swing out to the sea. Head to the shore and climb the ruins. You can collect the collectibles along the way. Make your way to the top of the ruins and you'll reach a jungle path. There are guards patrolling the path so you have to take them out stealthily as part of the first optional objective.
Hide in the foliage and take out the guards silently. Continue ahead and you'll find two guards. You can double-assassinate them from above using a tree branch behind them. Continue forth and you'll encounter a split in the path. Both passages will lead to some walls with a lone guard patrolling.
Take him out and instead of following the objective marker, turn to the left to find a small waterfall and a stone wall. Go past that and there's another lone guard walking around. Take him out to loot the chest nearby. There's also a shanty here and a white jaguar that spawns here as well. The jaguar is dangerous so you have to kill it quickly; otherwise it will keep doing hit-and-run attacks until you succumb. Don't forget to get its skin once you kill it. Return to the main path and follow the objective marker. Take out the guards along the way.
You'll eventually find several stationary guards along the trail. Avoid any confrontation to make sure your optional objective is still intact. You just have to be careful of the only patrolling guard. There's an off-trail to the right which will allow you to bypass them completely. You can just pass them and run towards the path to the right directly then open the chest along the way.
Hop on the branches and trees until you reach an abandoned native settlement with several more guards – including a gunner. Hide in the foliage then tag the targets with your eagle vision to keep track of their movements. The gunner and the two guards on the ground are just walking around in circles. Move around the hut and take cover in the bushes nearest to their path. From there, you can let them pass a bit then double-assassinate them. If you want to go loud though, you can just get close enough and use your pistol to take out the gunner. Make sure to leave the area immediately and hide far away since the shot will attract the other guards. Once you've patiently and stealthily dealt with the guards, you can collect the animus fragment on top of the wooden platform nearby without any worries of being discovered.
Follow the path and you'll discover a small village where the target ship is docked. If you haven't been discovered, the first optional objective will be complete at this point and the second will be revealed. Since you can only do this when your target is unaware of your presence, you'll have to remain discreet and silent.
Employ stealth and take out the enemies without alerting nearby guards. You have to make your way to the bow of the ship since that is where you can get into the perfect position to attempt the second optional objective. Upon reaching the bow of the ship, climb up and be careful not to be seen by the roaming patrols. You have to use the ropes connecting to the masts.
Once you're there, make your way to the main mast in the middle and climb down slowly to the grid of ropes on either side. Climb down enough for you to highlight a target below and for your assassination button to be enabled. Wait for the target to pass and assassinate him from above to complete the optional objective and the mission.