Relto is the first Age written by Yeesha. It was a gift to her parents, and its terrain and layout very closely resemble that of Myst, although Relto is much smaller. The Age has since been re-purposed to serve as a home for explorers who take the Journey.
The Linking Book given to explorers exhibits two unique capabilities compared to standard Linking Books. First, when attached to a person, it has the ability to follow them through the link, so that it is never left behind when traveling. This makes it a convenient "escape" tool in case an explorer finds themselves in a dangerous situation. Second, the book can be used while already in Relto—other books are non-functional in such circumstances.
Despite having only a Linking Book (as opposed to a descriptive book), each explorer has their own separate instance of Relto to call their own. This seems to be yet another unique capability made possible by Yeesha's deeper understanding of regestoy.
Relto is an island in the clouds, so high above the ground that it is obscured from view. The terrain mimics the layout of Myst Island, a gently-sloping mound of land with a small spire of rock jutting up on its southern end. A stone hut stands in the same relative place as Myst's library. A newly-claimed Relto is fairly barren—the ground is dry and covered only in short scrubgrass, and the hut has a simple thatched roof with no ornamentation.
Relto's appearance can be altered by its owner through the acquisition of Relto pages. These pages can be found scattered around various Ages and cavern locations. These pages and their ability to effect change within Relto are unique in their design, because they do not contain any D'ni writing. Instead, each one has a simple pictograph on it, depicting the sort of change or addition it makes when added. These pages are also unique because they are used in a Linking Book to affect the Age, rather than its Descriptive Book. Once a page has been added to a Relto Book, the feature it controls can be disabled simply by touching the symbol. Symbols for active features glow bright green, while inactive ones are a darker color.