Mare Tranquillitatis

Mare Tranquillitatis (静かの海) is a dungeon on the hidden fourteenth server, the Moon server. After the Catastrophe, it has become the place where Adventurers go before they revive and return to Theldesia.

Overview
When Adventurers first get killed, they will find themselves revisiting parts of their memories of the old world. As they wander around, they eventually find themselves on a sandy beach overlooking a body of water, and can see Earth. There, they sacrifice a small part of their memories in order to return home; since the process is instinctive, it is suggested that it is impossible for one to consciously resist it.

Server Information
When Shiroe checks Mare Tranquillitatis' information in The Changing Battlefield, he sees a screen with garbled text. Fans on 2ch deciphered it to reveal some more information about the server.

Trivia

 * Mare Tranquillitatis is a real lunar mare. Its name means "Sea of Tranquility."
 * The Interlude in A Sunday in Akiba mentions two other locations on the Moon: "Sky Labyrinth of Imbrium" (インブリウムの空中迷宮) and the "Sea of Soma" (神酒の海).
 * The "Sea of Soma" is a literal translation of the Japanese name for Mare Nectaris. Mare Nectaris is located south of Mare Tranquillitatis.
 * Imbrium is the name of a real lunar mare, but in this case it most likely refers to the Imbrian lunar geologic time period during which Mare Tranqillitatis and Mare Nectaris were formed. (The time period is spelled "Imbrium" in every language except English.)