I will never know what went through the mind of the National Park Ranger when we pulled up to the gate at the south entrance of the Grand Canyon National Park. It was around 5:30 am on a brisk April morning. We were seven guys in total, five Spaniards, and two Austrians, crammed, more or less, into a Ford rental van. All of us had been living in the United States for several years, all united by a common interest: ultra-distance-running.

“Are you guys planning on hiking down to the bottom of the canyon?” the ranger asked, like he had, probably, thousands of other visitors before us, through the rolled down driver side window. “Yeah,” Joaquin, who was in the driver’s seat, replied back calmly, expending no more energy than necessary at this early hour.

“Be sure to take plenty of water with you,” was the ranger’s advice, before he handed us our day permit and sent us our way. We were going to take plenty of water, alright, but we weren’t going hiking. We were there to run from the South Rim to the North Rim and back in one day, commonly referred to as the Rim2Rim2Rim run.

After some haphazardly executed warm-up stretches in the parking lot at Grand Canyon Village, we started our descent into the canyon. We headed down South Kaibab Trail, the busiest, most frequented route for both day hikers and backpackers to experience the Grand Canyon. I fancy running downhill, so I felt right at home, enjoying the crunching sound of the mix of sand and dirt underneath my trail running shoes as I was pounding down the trail. As the sun slowly rose, it colored the rock formations into deep earthy tones of orange and dark red. The air was fresh, but not cold. Perfect running weather, one could argue. Yet, I came to realize later, this was the easy part of this ultra-endurance adventure.

Ahead of the others, I made my way across Cedar Ridge and skirted the base of O’Neill Butte, a Supai sandstone tower, popular with rock climbers, before passing Skeleton Point, favored by many hikers for taking in sweeping vistas of the canyon from a lower altitude. At the Tipoff, another viewpoint, I caught a first glimpse of the Colorado River and entered what is referred to as the inner canyon. I still felt good and let gravity do the work, my knees seemingly unimpressed by all the downhill. Not before long, I reached the bottom, crossing over the river on the Kaibab Suspension Bridge, 75 minutes after departing from the South Rim and about six miles behind me.

Passing by Bright Angel Campground, I waited for the others to arrive and we regrouped at a picnic table in front of the Phantom Ranger Station. Energy bars and other snacks were consumed, the overall mood was positive. What followed next was a seven-mile stint through the Inner Gorge, a narrow canyon within the canyon, the trail being hemmed in by schist cliff formations on either side, with Bright Angel Creek flowing calmly in the middle. The only way, sadly, at this point, was up. We were now on the North Kaibab Trail, and while not terribly challenging, the trail was going slowly, but steadily uphill.

My watch read mile 13 when the inner canyon walls gave way to a more open scenery, as well as higher temperatures up to 95F (35C). A welcoming distraction in the landscape followed about a mile after Ribbon Falls, roughly .3 miles west of the main trail. The falls were carrying well below average levels of water this time of the year and, alas, we didn’t really have time for the detour anyways. By that point, I had formed a sub-group with my fellow runners Jürgen and Gaspar. The next milestones were Cottonwood Campground and then the Manzanita Rest Area, before starting the six-mile, 3300 feet climb up to the North Rim.

We had entered Roaring Springs Canyon, flanked by massive limestone cliffs that seemed to come closer and closer the further north we got. Eventually, the trail changed from merely hugging the canyon wall to half-tunnels being carved out the side of the canyon, evidence of an engineering marvel conceived in the 1920s.

Once we had reached the Redwall bridge at 6000 feet, running was finally out of the question for me. I had covered roughly 20 miles in about three and a half hours by that point, my water supply was running low, and the high energy feelings from the early morning were long gone. I dragged myself up the final climb and made it to the North Rim at 2pm, after 5 hours and 40 minutes, where Jürgen and Gaspar were already waiting. After gathering my thoughts, having a few sips of water and an energy bar, I realized that we had only gone halfway.

Somehow I missed the opportunity to refill on water at the North Rim, and by the time we had turned around and reached the entrance of Roaring Springs Canyon on the way back, I had depleted my supply. With the others nowhere in sight, I took a break and even though I didn’t have any way to treat the water, decided to run the risk of a severe stomach upset and refilled straight from Bright Angel Creek. Dunking my overheated head into the brisk water felt refreshing, and with the water, I could feel some energy coming back.

From this point all the way back to Bright Angel Campground it was an ever so slight downhill. And downhills I could do. Once we had entered the inner canyon again, the temperature worked in our favor. The worst of the heat had subsided. We again regrouped at Phantom Ranch, our legs, gravely beaten and hurting in various places, were covered in orange and beige colored dust from the trail. We refilled on water, had another snack or two, and tried to mentally prepare ourselves for the toil back up the South Rim.

It turned out to be brutal. By then, we had been on the trail for over 12 hours and running, let alone uphill, was impossible. So It turned into a hike back up the South Kaibab Trail, covering the six miles and 4600 feet of elevation in roughly two hours, a good half of it in the dark.

After the last switchback, I remember making out the silhouette of Joaquin, waiting at the top of the trailhead. I hugged him on arrival out of sheer happiness and stumbled into the backseat of the van, were part of our group was already waiting. It was close to 9:30 pm. It had taken me a tad over 15 hours to complete 42 of the toughest miles I ever experienced.

Once Jürgen arrived, Joaquin commandeered the van south, in the dark, towards the park exit. Luckily the park ranger from the morning wasn’t there to ask us how it all went.