The Aquasphere (アクアバリア, "akuabaria" or Aqua Barrier in Japanese) is the blue membrane-like substance that surrounds Ephinea.
As a whole, the Aquasphere itself is composed of primarily water eleth. In early concept art, it's stated that it's composed of liquid nanoparticles. It sits between Foselos and the surface, and thus due to its position it largely acts as the atmosphere for Ephinea.
Because of its membrane-like structure, it's effective against impacts from both outer space as well as inside it. From the surface, you can't see the Aquasphere due to its low visibility from the surface. The thickness of it allows for only the inner ring of Foselos to be visible in the Ephinean sky. Fodra is completely hidden from view.
Foselos is in charge of maintaining the Aquasphere, taking in water eleth from the pole points and releasing it back towards the outer area of the sphere through the inner ring. Foselos' rotation seems to be a part of its maintenance cycle.
 Method of Travel
Due to its thickness, traveling through the Aquasphere is not an easy task! During the game, Asbel and the others had to use two large Heat Ray Cannons located in the Snowshroud Ruins and Sandshroud Ruins in order to pierce a temporary hole through which the Shuttle could travel. It can be assumed that during Ephinea's initial set up, the canons were used in order to facilitate ships to and from Fodra. However, it's unclear how exactly people from Fodra were able to make trips to Ephinea due to the absence of the same kind of cannons. During the game, the party uses a Derris Bit in order to pierce through the Aquasphere themselves, however there's no conclusive evidence to suggest that ancient Fodrans used the same methods when traveling to Ephinea themselves.
 Trivia and Data
- The Aquasphere is known by another name, "The Sea of the Sky"
- The distance from the surface to the Aquasphere is approximately 15K meters, or about 49,212 feet.
- It has a thickness of approximately 30 meters, or 98 feet.
- ↑ Picture from the Day One Edition Art Book, translated by Kirvee
- ↑ Picture from the Day One Edition Art Book, translated by Kirvee, "The Aquasphere can’t be seen very well as it’s not that visible and only the interior of the Ring can slightly be seen. Fodra can’t be seen at all."
- ↑ Picture from the Day One Edition Art Book, translated by Kirvee, "The Ring serves to carry out maintenance of the nanoparticles by taking in the particles from Point A and releasing them from the inner Ring."
- ↑ 'It spans across the whole sky and is also called “The Sea of the Sky”.', from the Graces f Perfect Guide Glossary
- ↑ 5.0 5.1 "Distance from the surface to the Aquasphere = 15,000 meters (AKA ~49,212 feet or 9 miles)", from the concept art diagram in the Day One Edition Art Book, translated by Kirvee.