The Hidden Kini-Nui Passage is a secretive, unmarked road that allows quick travel from the northeast of the island to Kini-Nui, in the southwest.
The hidden passage begins under Gali's Falls; a tunnel is hidden past the curtain of water, accessible only by boat.
Past the falls, a damp cave winds its way through the rocky cliffs bordering the Hura-Mafa River, eventually emerging at the top of the cliffs.
Following southward along the edge of the cliffs for a while, with greenery becoming more and more abundant, the path comes to a gap in the cliffs around a bend in the Hura-Mafa River. A short wooden bridge spans the gap. The Old Fusa Path also uses the same bridge.
The path continues following greenery-laden cliff-tops, curving southwest to skirt the mountains of Ko-Wahi.
The greenery begins to disappear as the rocky cliff faces begin growing on either side of the path. Occasionally, large boulders will block the path; rockslides are common here. The path continues through the rocky pass, approaching the base of the Mangai Volcano.
After the path turns and follows a western direction, the path begins ascending the northern slope of the Mangai. Snow begins to accumulate on the path due to the altitude, as the path continues west across an icy ridge in the slope of the volcano.
A large statue of a Toa's head eventually blocks the path through an open, snowy bowl canyon, only openable by a peculiarly-shaped key.
Past the head statue, the path continues through another, smaller rocky pass, as the snow begins to disappear. Kini-Nui is visible in a clearing in the distance.
The path continues down a rocky cliffside into the jungle of Le-Wahi below. The path cuts straight west-southwest towards the Kini-Nui clearing.
The Hidden Kini-Nui Passage is the quickest route to Kini-Nui from any of the eastern villages. It provides a much more direct route across Mata Nui rather than having to travel around the bulk of the islands's desert or jungle biomes, and avoids traveling through mountains, for the most part.
The path cuts through several Wahi, and even traverses the slopes of the Mangai Volcano itself. The geological, geographical, and biological features of these Wahi are apparent along the Hidden Passage.
The passage itself is mainly unmarked, but follows a navigable path through many of the islands's cliffs, rocks, and between the faces of mountains and volcanoes.