We're fairly certain that many of you have heard of this place at some point. A kingdom that became submerged underwater, never to be found again... until now! Or, in Skyrim to be a bit more specific.
The reason Atlantis is on the list is purely because of its location. You might talk to a specific person, or come across some kind of an event, which sets the quest to discover the city in motion. The best part is, it'll all be underwater, so make sure to pack a lot of potions of waterbreathing (unless you're an Argonian)!
Let's also be honest here. There isn't much going on deep underwater in Skyrim. There really isn't anything to explore or discover. This location, if composed as a mod, would be perfect for exploration and adding fresh new ideas to a neglected part of the game. Who knows? You might also come by a number of unique characters, weapons, and gear that pertain to Atlantis.