The Milk Sea was one of the many locations where the once-wandering village of Thriff rested its foundations as the Guildmaster Orkan constantly moved the town in an attempt to find a more benevolent climate for his terrible hayfever. During the three month period when the space-shifting village was trapped beneath the milk sea, the people of Thriff used a great deal of cheese to thwart starvation.

SOURCE(S): Zork: Grand Inquisitor