Jagged ridgelines darken and blur in the dim light. A palette of blues merges into thick, bland gray. I lean my head forward to rest on the rock wall in front of me and pay out slack listlessly as the rope twitches to Chantel. In the murk of early morning, we find ourselves 2,500 feet up the Denali Diamond, with another 5,500 feet of mountain above. We’ve taken turns belaying as we explore the “snow band” for bivy spots. So far, we’ve found only shallow ice over steep rock. After 30 hours of climbing, my fatigue dulls the brilliant Alaskan skyline. I forget the gift of moving in such extraordinary terrain. I might as well be checking out at the grocery store.

The rope is still. Maybe she found something. “Oy! How you doin’, lady? What do you see?” “I got nothing!”

Chantel returns to the belay, bleary eyed. She chops a small bench as I build another anchor and brew water. We put on all our clothing and sit—so exhausted that for almost two hours even this tiny ledge provides enough of a respite for us to sleep.

Thirty hours earlier, Chantel and I had stood at the base of the Denali Diamond at midnight. “Ready?” Chantel asked. She pulled her hood snug over her helmet, Kiwi coil over her shoulder. The darkened granite of the southwest face towered over us, impartial and still. “Can’t wait,” I said. “Have fun up there.” Our long stay at the 14,200-foot camp on Denali’s West Buttress Route, waiting through blizzards and high winds, had simplified this moment—an initiation of upward momentum. As Chantel cleared a path through the bergschrund, grains of hard snow clattered downhill with a metallic sound. Quickly, she bridged the gap and led on, steadily, efficiently. I’m lucky to have such a solid partnership; it’s straightforward to commit. The slack dissipated, and we began to climb together, our movements sure and our minds clear.

After our two-hour nap, we continue to a better ledge, put up our tent, and sleep all through the afternoon and night. In the morning, we start up toward the crux pitches of the route, embarking on what would become another 30-hour push.

Hours blur. Our progress is marked by minute shifts in the landscape: golden granite walls merge almost imperceptibly into smoky gray. The rock steepens as picks and crampons blunt, nearing the shadow of a giant roof. Ice remains scarce.

The sun circles low, lighting Mt. Foraker in a blaze of orange before dipping briefly beneath the horizon. Chantel weaves her way through a band offragile rock in the steep dihedral. I admire her graceful, methodical approach: never rushing, always in control. Following in muted gray light, I stem amid a cemetery of precarious blocks. “We finally found some choss,” I say. “Great job.” Chantel smiles when she hands me the rack. “Thanks, lady. You’re up.”

I step up cautiously and lean sideways on my tool, striving to get some rest while maintaining the same direction of force. I strain to find a hint of sunriseamid the shadows of an indistinct skyline. High on the face, perfectly parallel cracks require creative twisting and camming with our tools, while our crampons scum on granite dishes. Occasionally, we pull on a piece to surmount a roof, stunned to find the wall suddenly so featureless. Where did all the footholds go? Warily, I torque my tool over another small overhang, moving up. Above the roof, the angle eases, and I scramble to the snowfield above.

Chantel follows, wrapped in her belay jacket, as morning light brushes the highest peaks. Exhausted, we nearly knock our stove down the slope as we bumble to brew up. Another 4,000 feet of snow and ridge soar above toward the summit. But the giant headwall is now beneath our feet. Our prolonged efforts have felt so natural, almost magnetic: We’ll continue to endeavor upward, until it makes sense to go down. What else is there to do?

Chantel Astorga and Jewell Lund climbed the Denali Diamond (7,800’, Alaska Grade 6, 5.9 A3 M6 WI5+) from June 15–19, 2015. This story is adapted from an article in Alpinist 52, with permission; a longer version is available at Alpinist.com.