"Voyage into the Unknown" by Roderick Coover is an historical non-fiction hypertext about the first geographic expedition down the Colorado River in 1869. The three-month journey was led by John Wesley Powell who, with his eight fellow boatmen, departed from Green River City in northern Utah towards the Gulf of California. Coover investigates in the question of how we come to know and imagine an "unknown territory" and provides the answer with the navigational technique he applies in his work: an interactive panoramic environment with a digitally re-worked map of the journey, in which the user navigates though the desert landscape using a seamless, horizontally scrolling interface.

The reader, who takes the perspective of crew member George Bradley, faces an unknown literary space he can choose to explore in several different ways. He can either use red arrows to move back and forth within the landscape or use the "key" numbered from one to twenty that recalls a chapter-like navigation. In order to "read the unknown territory", the user is forced to explore the map that is marked with points of interest. These markers (abbreviations that are explained in an introductory agenda at the beginning of the piece) work like hyperlinks that, once activated, name places passed, people the group met or events they experienced.

A diary-like narrative unfolds in short excerpts of texts that reveal what happens when the crew is declared dead, and how they manage to survive in "the darkest hour" when sustenance decreases each day. The narrative is contested with researched facts that intertwine with actual diary accounts and works by John Wesley Powell, along with additional publications by other crew members (George Bradley, John Sumner, and Frederick Dellenbaugh). Coover also integrates primary visual works by E.O. Beaman, John Hillers, and Thomas Moran with new and original writing, artwork, and interactive devices.