Complete every activity in a single location. [Bronze / 10G]

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.