In Hopi mythology, the sacred opening to the underworld is called the sipapu.
A sipapu is represented physically by a small round hole or depression in the floor of a kiva, the ceremonial room used by Hopi and other Pueblo peoples. Symbolically, it is the passage through which ancestral beings or the first people emerged from an earlier underworld into the present world. The same opening is also associated with the route by which the dead return to the underworld.
Hopi emergence traditions describe movement through successive worlds, often called the First, Second, Third, and Fourth Worlds. In one widely recorded version, people reached the present Fourth World through the sipapu after earlier worlds were destroyed or became unsuitable. Some accounts associate the original sacred opening with the Grand Canyon, although Hopi traditions vary by community and not all versions emphasize the same route.
A kiva is the chamber, not the opening itself. Mesa is a type of landform, while Pahana is a separate Hopi prophetic figure or concept. Thus sipapu is the precise answer to the question.