For this achievement you will need 5 in-game achievements which are:
Gold Coast Adventurer- For this you need to finish 17 quests in the Gold Coast: 8 of which are from the Dark Brotherhood questline alone, 2 are found in Delves, 7 which are tied to the
Gold Coast Connections achievement, and one from the Kvatch Arena
Defender of the Gold Coast- These are the 2 World Boss Locations: One is the Kvatch arena which is actually pretty easy if you have 2 other people with you and there are a lot of other players in Kvatch. The second is Tribune's Folly which is much much harder, you'll need at least 4 players to even stand a chance against this boss.
Gold Coast Pathfinder- These are the locations on the map that appear as an eye: There are 6 in total and are easy to find as the Gold Coast is very small. You'll most likely find all of them while completing quests.
Silencer- This is acquired after completing the last quest in the Dark Brotherhood questline. There are 8 in total.
Gold Coast Delver- There are 2 delves in the area that will need to be cleared: Hrota's Cave and Garlas Agea. They are easy to clear and will be encountered when completing two of the quests for the
Gold Coast Connections achievement.
The only thing that will take time for this achievement is the Adventurer one- As I said, there are 8 total Dark Brotherhood questline related quests and you need to level up the skill line to obtain the next quest. You will get the last quest once you've reached Skill Level 8. The way I found to level this up quickly is to keep doing the Marked for Death quests given in the DB Sanctuary. Another note is that since these quests will take you other territories in the other Alliances, I found that by simply abandoning quests until you get the ones that will take you to territories your alliance is in, it will save you a lot of time. I'm in the Aldmeri Dominion alliance and only did Marked for Death quests that took me to Auridon, Grahtwood, Greenshade, Malabal Tor, or Reaper's March.
And that's all there is to it, it can be a little time consuming, but not really difficult, you'll most likely obtain this after completing the
Silencer achievement.
Good Hunting! Leave any comments if anything needs to be cleared up!