The principal sphere of influence of the Seven Seas Hall was indeed within the demon-ridden Inner Sea.
Within the Inner Sea, the Seven Seas Hall had established a total of seven colossal sea cities.
They are Linghai, Zhenhai, Tianhai, Ninghai, Yuhai, Minghai, and Jihai.
These seven sea cities were each far apart from one another, scattered throughout the Inner Sea.
Moreover...
They were all constructed from entire islands that were transformed, each one immensely large, the smallest among them comparable in size to the three largest islands of the Thousand Islands Domain.
The seven sea cities were not only sizable but also extremely robust. The Seven Seas Hall specifically dispatched top Formation masters to establish powerful barriers around them.
With these formations, they could not only withstand attacks from various Demonic Beasts within the sea, but even in face of assaults from other forces, these colossal sea cities remained unscathed.
