Kill FeeFee the crab.
Reach the Galleon
Speak with the Endurance crew to progress the Chatterbox trophy/achievement and then head south across the broken pier. Before climbing up the ladder, head south and check the ocean for a Mine (4/10) and then climb up to collect some Salvage .
Slide down the rope and check the ocean to the left for another Mine (5/10) and then swing to across the the rocky wall to reach the Galleon. [100 XP]
Collect the Block and Tackle
Wait for the two Solarii to finish their conversation and then rope arrow the first man off the ledge before finishing off his companion. Make sure to loot the Salvage in a net and then cross the gap and head upstairs, scrambling the wall to shimmy up to the deck. You can now shoot the pulley to drop the Block and Tackle and drop the mast. [100 XP]
Return to Jonah with the Block and Tackle
Cross the mast and kill the two Solarii on the other side and then turn the corner to enter the cabin for the Brown Jade Ink Box . You can now use the ziplines to reach the beach and return to the camp for a scene, gaining the Compound Bow from Jonah. [400 XP]