The Inner Sanctum is the middle of Highline's three roughly equal segments, covering 22.1 miles with 1,871 feet of climbing and 2,025 feet of descending when ridden east to west. It begins on fantastic Sedona-style red rock slabs, similar to those at the end of Gathering Waters — yes, red rocks, just like the ones you'll find in Sedona. But once those slabs conclude, the trail transitions to flowy, machine-built singletrack that carries you deeper into the heart of the route.
You'll hear people refer to Highline as "purpose-built singletrack," but I'd take issue with that assessment. Instead, I'd characterize the trail as modern machine-built multi-use trail. Highline is open to hikers and equestrians as well — we saw several horses and mules during our ride — and the tread and corridor are definitely constructed with these users in mind. That said, many sections provide a kinesthetic swoop and flow that mountain bikers will eat up, and nowhere is that more true than on the Inner Sanctum.
This middle section is home to the most extensive rerouting on the Highline, consisting almost entirely of brand-new singletrack. As of 2026, this trail could use a few more tires in places, as it's starting to get grassy. But now that the entire route is complete, the locals anticipate that traffic will pick up and the trail will get burned in. Like the rest of Highline, the difficulty holds to a solid Arizona intermediate/blue rating, and the bulk of the tread is sandy with sandstone rocks — making the Inner Sanctum a flowing, swoopy stretch right in the middle of one of the finest backcountry singletrack rides you'll ever do.
