The Silence Bookstore is not located on the mainland, but still at sea.
According to the address given by the City Lord, it is precisely that area considered a forbidden place, the Endless Sea. Over the years, ships in the Endless Sea have only entered and never left. Whether they went there deliberately to explore or were inadvertently swept in by sea storms, there's no coming back.
This has shrouded the Endless Sea in a veil of mystery.
However.
From what was learned from the City Lord, the actual reason is that the Endless Sea often has dense fog, almost never dissipating throughout the year. Moreover, there are many fierce Exotic Beasts in the sea, like the Deep Sea Demon Whale from the Free Federation, whose hometown is in the Endless Sea.
Therefore, regular ships heading in there are basically one-way trips.
Plus, with the Silence Bookstore located there.
