Assassin's Creed 3 – The Ruins of Cerros
This is available only for those who preordered the game and got access to Captain Kidd's Sawtooth Cutlass. This mission becomes available after you have gained access to the Aquila. This naval mission is a bit challenging so be ready.
Start by just heading straight through the tunnel until you reach the pool in front of you. Have Connor jump onto the 2 rock pillars and use those to reach the opposite side of the room. Climb up the wall moving slowly to the right to keep with the hand holds. Continue to the top then head over to the left. On the other side you will find the exit from the cave and up into the jungle itself.
Once in the jungle start toward the way point. Climb the ruins of the Mayan temple until you come across a large tree to the left. Start your climb up it and then over to the right, through the V-branch and out onto the limb in front. Take that over to the cliff face and jump to it. Climb up and onto the ledge above after that tense jump.
Head up the stairs and over to the left. Continue up the stairs then just press on left when Connor cannot find any more. You know you are on the right track when Connor slides under a tree and almost goes over a ledge. Head forward over the next gap. On the far side turn to the left and climb up onto the hand holds to the left of the vines. Take those to the left then start upwards as soon as you can. Head across the stonework and jump from the third outcropping to clear the gap you just climbed up from. Move forward around the corner to the left. From there just jump the gap and head to the left, climbing up the exposed masonry. A cutscene runs where Connor almost reaches the treasure but the age of the temple works against him and he just survives the fall.
Head to the left and up the wall to start your climb back up. You will notice a partly destroyed pillar. You want to run up that and jump over to the intact one. Climb upwards from there and then go around the corner in front of you to the right. Move carefully onto the plant roots that network the roof of the room that Connor landed in and take them out over the room once again. Use them to get across the room.
Once on the other side, free run across the pillars to reach the opposite side then shuffle to the right. Get to the edge then back eject over to the next part of the path. Climb over to the left and up from there. Connor will climb out onto an animal head fountain, go left from there then press upwards.
Turn left at the top of that climb and run to slide through the small opening. Turn left and swing across the gap using the tree roots above you. Once on the other side head to the left and around the next corner. Jump the gap and climb upwards across the masonry. At the top turn left and head over to the raised table. Interact with it to claim your reward of the Sawtooth Cutlass.