Once the schooner is flaming and incapacitated, sail close to it and begin the boarding process. Use the spyglass to find a schooner, then once you're within 300 meters, fire the hook from the front of the ship a couple of times to incapacitate it. Head back toward the ship and meet up with Edward's friends on the beach to begin the next mission. Once you have at least 18 recruits, head back to the tavern to complete the mission. Run at the hanging plank as quickly as possible and take down the guards, then free the captain before he hangs for too long. When you reach the middle of town and have to free the captain, you have a very limited time to do so. You can also obtain a fragment and synchronize from this section of the building. When you reach the larger facility on the northeast side of the city, head around to the north side of the building, then climb up and take out the guard. The small numbers of guards scattered around Nassau, watching over the captives are fairly easy to contend with. You need to recruit crew members, which means freeing pirates from captivity. Travel to Nassau and speak to Adéwalé to begin the next mission. Speak to Adéwalé to complete the mission. You can use one of the two row boats to return quickly. Once you've crafted the two items, meet up with Adéwalé back on the ship. If you slowly move toward a group of ocelots, you can climb a tree to get the aerial kill for the second optional objective. Use your gun to kill the animals to make it easier and obtain one of the optional objectives. Ocelots are found all over the island, while iguanas are mainly found along the northwest portion.
Kill and skin two iguanas and two ocelots, then craft the resulting items into a pistol holster II and a health upgrade I.
When you get close, get off the ship and swim to land. A complete walkthrough of Assassin's Creed 4 Black Flag's third sequence.