Atlantis is an advanced underwater city made entirely of tubes. Upon entering Atlantis you will notice three separate paths: the left leads to the pokemon center, the right leads to the pokemon mart, and the middle path leads to the gym. Atlantis is the largest city in Pokemon Reborn and it is very easy to get lost if you do not know your way. Across from the gym you can find the entrance to the unfinished Victory Road area. Even though the entire city is underwater, no pokemon can be found in Atlantis.
Atlantis is located at the top of the waterfall found in the Ghost Forest. Upon entering, you will see a vault. Enter the vault and get to the end of the tunnel and you shall arrive in Atlantis.
The city of Atlantis is the home of the Water type specialist Atlanta.