Radessia is a large, mostly desolate landmass with few inhabitants other than Kimlasca's settlements. It yields a rugged, sandy terrain with fierce winds and steep mountains and cliffs, which make a vast majority of the continent inhabitable. A single waterway, the Nirni River, cuts through the center of the continent and stops.
- Sheridan - Famous for fonic technology and devices, this is the birthplace of the Tartarus and Albiore. Also known for rare accessories.
- Port Sheridan - A harbor which exports goods to Sheridan. A ferry to Kimlasca also leaves from this port.
- Nam Cobanda Isle - An island run by the Dark Wings. Difficult to access due to its tight security. Fonic technology and artes are a common sight here.
Ortion Cavern (ワイヨン鏡窟 Waiyon-kyoukutsu?, "Wyon Mirror Cavern") is a cave complex accessible only by sea. Its only entrance lies in a lagoon on Radessia's southern side, while the other inputs are blocked by whirlpools. Within the cave are lifts and aquatic monsters, and deep within is a machine used for replica research. Originally, the God-General Dist used Ortion Cavern for his experiments on replicas, and the cave itself is named after him, albeit his true name.
The group ventures here after hearing about it from researchers in a laboratory in Belkend. With Fon Master Ion waiting in the Tartarus, the group proceeds into the cavern, Asch currently replacing Luke fon Fabre, who is back in Yulia City with Tear Grants. In the deepest part of the cavern, the group discovers a small fomicry facility where two cheagles are imprisoned: an original and its replica. Jade Curtiss explains that fomicry can have negative consequences for the original test subject, causing Natalia Luzu Kimlasca-Lanvaldear to worry about Asch, but Jade dispels this worry by stating that Asch is still alive and well after seven years, eliminating such a threat. As the group leaves, they are attacked by a sea monster, which they defeat, but this encounter is followed by an earthquake, which Asch suspects is southern Rugnica plunging into the Qliphoth. The group leaves afterward.
- A barren stretch a land where hardly anything grows. Usually avoided by humans. Several monster sightings have been reported here.
The Meggiora Highlands (メジオラ高原 Mejiora Kougen?) are located in the center of Radessia and can be reached both by land and by the river. Depending on which route is chosen, different areas of the highlands can be reached. The climate of the area is rather dry, and the highlands are haunted by strong winds, yielding the most unfavorable conditions of the continent as a whole.
The group visits the area in order to save the pilot Ginji, who crashed the Albiore there in a practice flight. The protagonists split into two groups to meet on two opposing cliffs, the Albiore with Ginji inside hanging between them. Within twelve minutes, the groups overcome the difficult monster battles and make their way to Ginji on opposite sides, securing the Albiore and returning him home safely. However, this changes if the player is unable to reach the location in time, and Ginji will instead die, slightly altering other events in the story. The group also ventures here a second time in order to search the Sephiroth Tree. For this purpose, the Albiore must be used to traverse the Nirni River.
- Located in the depths of the Ortion Cavern. The remains of Dist's questionable experiments have been left here.
The Abyss, the Replica Facility (深淵のレプリカ施設 Shin'en no Repurika Shisetsu?, "Replica Factory of the Abyss") is located within Ortion Cavern and can only be accessed on a second playthrough or later after having completed the sidequest involving the rescue of Shiba, as well as the sidequest in the eastern part of Ortion Cavern. Speaking to two men in Sheridan, followed by Shiba, will allow entrance to the dungeon. Shiba accompanies the group to the facility, mining away blocked door entrances in exchange for Gald while his health periodically depletes as a result. If at any point Shiba's health depletes entirely, the player will be returned to the entrance of the dungeon, albeit with all passages Shiba mined still cleared.
Within the many rooms of the maze-like dungeon, the group finds strange machine generators that must be destroyed using Mieu's smash attack. A large number of the rooms contain nothing, while others yield treasure chests with valuable items, healing springs, and consequential traps. Halfway through the large facility, the group discovers replicas of the God-Generals Arietta, Largo, Legretta, and Sync that Dist created and sealed within the dungeon. The replicas do not speak but instead fight against the group, the Legretta replica entering the fight only once one of the replicas of Arietta, Largo, and Sync is killed. In the absolute deepest part of the facility, the group finds and faces a replica abomination called Replicantis.