1. Collectibles
1.1. All Mayan Stelae Locations (Vault Raider)
1.2. All Unlockable Tavern Locations (Barfly)

2. Miscllaneous
2.1. Excavator – Find a buried treasure.
2.2. Hungover – Wake up in a haystack.
2.3. Silence, Fool! – Kill a guard ringing a bell.
2.4. Owned – Complete every activity in a single location.
2.5. Killer Killer – Harpoon a killer whale.
2.6. Siren Song – Rescue pirate hostages by distracting enemies with “dancers.”
2.7. Redingote Up! – Craft the Hunter outfit.
2.8. Wild West Indies – Kill 4 enemies in a row using multi-pistols.

Vault Raider
Unlock the secret door in Tulum.
To unlock the secret door in Tulum you must solve all 16 Mayan Stelae puzzles. The first puzzle is part of DNA Sequence 4, Memory 1 and cannot be missed. After finishing this memory, the other stelae will become available. Some of them are on islands of dangerous ocean zones, so you should get your ship upgraded and continue with the story to make all locations accessible.
You can also see the stelae locations on your map if you synchronize the viewpoints of their respective area. To check which ones you have found, open up the progress tracker and select the “Mayan Stelae” tab. It provides an overview of islands that contain these secret puzzles.

Once all 16 puzzles have been solved, you need to travel to Tulum. There will be a marker on your map, saying “Mayan Outfit”. Go there and open up the door to unlock the Vault Raider trophy / achievement, along with this new and unique outfit. The Mayan outfit deflects bullets from enemies shooting at you!

Here are the exact coordinates for each stela:

#1 – Great Inagua (Acquired during DNA 4, Memory 1)
#2 – Cat Island (Coordinates: 734, 694)
#3 – Matanzas (Coordinates: 343, 642)
#4 – Cape Bonavista (Coordinates: 179, 593)
#5 – Tulum (Coordinates: 70, 405)
#6 – Pinos Isle (Coordinates: 334, 476)
#7 – Pinos Isle (Coordinates: 342, 478)
#8 – Tortuga (Coordinates: 876, 377)
#9 – Long Bay (Coordinates: 525, 253)
#10 – Isla Providencia (Coordinates: 502, 44)
#11 – Isla Providencia (Coordinates: 502, 44)
#12 – New Bone (Coordinates: 431, 116)
#13 – Misteriosa (Coordinates: 303, 199)
#14 – Misteriosa (Coordinates: 296, 196)
#15 – Santanillas (Coordinates: 217, 245)
#16 – Santanillas (Coordinates: 221, 242)
Unlocking the secrect door in Tulum (Coordinates: 70, 405)

Barfly
Unlock all taverns.
There are a total of 8 taverns that need to be unlocked. You simply walk up to the barkeeper, watch a short cutscene and beat up the bandits. You can see the taverns on your map if you synchronize the viewpoints for the respective area.

The tavern locations and their coordinates are as follows:
#1 – Andreas Island (573,720)
#2 – Salt Key Bank (496, 629)
#3 – Crooked Island (808, 545)
#4 – Arroyos (192, 565)
#5 – Corozal (37, 266)
#6 – Grand Cayman (392, 325)
#7 – Kingston (623, 172)
#8 – Ile à Vache (839, 137)

Excavator
Find a buried treasure.
To find a buried treasure you must first obtain a treasure map. One of these maps can easily be found on Mariguana Island, at the coordinates 878, 539. Go pick it up and you will be shown a picture and the coordinates of a treasure. This particular treasure can be found on Andreas Island, at the coordinates 575, 717.
To unlock the locations of other treasure maps, you can talk to the barkeepers of taverns or just explore the world and synchronize viewpoints.

Hungover
Wake up in a haystack.
To get this trophy / achievement you need to keep drinking at a tavern until you pass out. A tavern can be found in Nassau. It’s one of the first locations you will visit during the main story. Walk up to the bar and interact with the bottle to start drinking. You have to drink at least 5 times to pass out.

Silence, Fool!
Kill a guard ringing a bell.
This can be done wherever a warehouse is. Warehouses are at farms and have a restricted area around them (shown with red color on world map). They will be marked on your map if you synchronize viewpoints. One can be found in Nassau, at coordinates: 633, 784.
Once you enter the restricted area you should see the alarm bell on your HUD. Get noticed by an enemy and wait for him to ring to the bell. Quickly kill him with a melee attack when he starts ringing the bell to unlock this trophy / achievement.
You can also do this at warehouses that have already been looted. The enemies will respawn after a while.

Owned
Complete every activity in a single location.
A great place to do this is the island called “Florida” at coordinates 409,815. When you scroll over an island on the world map, you can see which activities it has to offer. That’s usually just some collectibles and viewpoints. Luckily, Florida has very few of them. Synchronize the viewpoint, collect the two animus fragments, open the treasure chest, and pick up the bottle message to unlock this trophy / achievement.

Killer Killer
Harpoon a killer whale.
Killer whales can be found in the ocean part named “Cruz”. First off, you should capture the fort of this area to see the killer whale symbol on your map. The fishing locations can vary, so check your map. Also upgrade the harpooning statistic of your ship by upgrading the harpoon strength and harpoon storage.
Fishing locations are highlighted on the ocean when you get close. Interact with one of these spots to start fishing. Defend your boat and keep throwing harpoons at the whale until it dies.

Siren Song
Rescue pirate hostages by distracting enemies with “dancers.”
To do this you must let some of your crew members die. Just board an enemy ship and sit back while your crew does the fighting. Many will die. After that, head to Kingston and go to coordinates 623,172. There is a restricted area where two enemies are aiming at captured pirates. You can hire some dancers nearby, just up the street. Send the dancers to these two enemies and once they are distracted sneak behind their backs and free the pirates.
If this event does not appear (despite having lost a lot of your own crew), then fast travel to another island and come back later.

Redingote Up!
Craft the Hunter outfit.
Crafting the Hunter Outfit will cost you 11,000R. Go to any general store and buy the red howler monkey skin (5000R) & white jaguar pelt (6000R). Now open up the crafting menu, scroll to the very bottom and choose to craft this outfit.
If you don’ want to waste that much money, you could make a backup of your save game before doing this (e.g. on an USB stick) and copy it back afterwards.

Wild West Indies
Kill 4 enemies in a row using multi-pistols.
First off, craft all pistol holsters. You can buy the required crafting items from any general store if needed. So you don’t have to hunt down the animals on your own. Also buy and equip the “cannon-barrel pistol” for one-shot kills. All you need now is a group of at least 4 enemies. You can do this pretty much everywhere. Just walk up to them with the pistols selected in your weapon wheel and press triangle (PS3) / Y (X360) without aiming manually. Each shot should kill an enemy and this trophy / achievement is yours.