The Nankoweap Granaries are located in the Grand Canyon National Park near Marble Canyon, Arizona. The granaries are most often visited by Colorado River rafters. It is possible to hike to the granaries via the Nankoweap trail but be advised that the trail is classified as the MOST difficult named trail in the Grand Canyon. The trail is unmaintained, very primitive, and has a lot of exposure in places, with an elevation drop to the river of 5,640 feet.
The ‘Nankoweap Trailhead’ can be entered into your driving app for turn-by-turn directions. From Marble Canyon it will send you down the Buffalo Ranch Road and then onto Forest Service Road 8910. For the other trailhead you can enter the GPS coordinates (36.30314, -111.99466) and it will probably route you through Jacob Lake if coming from Marble Canyon or the Ryan Road if coming from Fredonia.
Included with this post is the GPS file and map that we plan to use for our first visit. If you don't want to wait for us to get around to it feel free to try the GPS file and map for yourself. With no guarantee, of course, but they most often prove valuable for us.