For this Achievement you need a online connection and a Uplay Pass. Now you need to find on your own the “Royal Convoys”, “White Whales” and a “Social Chests”. If you have friends that play on the same Platform as you, they (and you) will automatically share this location for a short period of time and you will see the locations on your map.
Royal Convoys and White Whales locations will be all over the map, Social Chests you will don’t find on the open world map, you need to search trough islands. It’s not enough to visit a viewpoint, you need to move around to find them. All Locations are random, so i can’t give you any coordinates.