Across Rocky Mountain National Park in a Day


I’ve been lucky enough to have RMNP in my backyard for the past 5 ½ years. The opportunities to hike, backpack, camp, snowshoe, ski and climb have kept me as excited about it today as I was during my first visit as an adult back in 2005. I’ve spent lots of time in my Denver apartment poring over the map of “The Park.” One day, I realized that there were a combination of trails that could carry an intrepid hiker all the way from the east side below Longs Peak, to the lesser-visited west side, a few miles north of Winter Park. I added up the trail mileage and said to myself:

  1. “That’s 25.5 miles. Wow.” Then,
  2. “I ran a marathon once, years ago, and very slowly. But I finished it in one day. That was 26.2 miles.” Then,
  3. “Well, this hike across The Park is ONLY 25.5 miles.”

The “Rim-To-Rim” hike in the Grand Canyon has made its way on to an increasing number of hikers’ bucket lists in the past few years, for good reason. It packs in the most scenery possible in one outing, in the most famous canyon in the world. It’s doable for most folks as a 3-day backpacking trip, and more and more people are attempting the 23-mile route in one long day of well-hydrated hiking.

And plenty of people have done the Rim-To-Rim hike in one day. And lived.

(photo by Syd Jones)

Syd, my girlfriend Steph and I left Denver at 2 a.m. on a Saturday in June, parked the car at the Longs Peak trailhead on the east side of the park at 4 a.m., and started walking by headlamp. In the trail register, we proudly wrote “Green Mountain Trailhead” as our destination. We watched the sun paint the Diamond on Longs Peak red, then orange, as it rose over the eastern horizon, and we topped out on 12,080-foot Granite Pass after less than 4 miles. We coasted downhill almost 7 miles, refilling our water bottles at a creek near the Glacier Gorge Trailhead, where fresh visitors were starting their hikes in the opposite direction of us, from the parking lot about a half-mile away.

(photo by Syd Jones)

At Bear Lake, which is a mere 256 feet from the Bear Lake trailhead parking lot (according to the sign), we paused for a midday lunch. We agreed to start hiking up to the top of Flattop Mountain, keep an eye on the weather, and decide near the top whether or not to continue to the other side of the park. Our pace slowed as we climbed to higher than 12,000 feet for the second time that day, and we hit the aptly-named summit of Flattop in the early afternoon. A stiff cool breeze buffeted us at the top (which you wouldn’t know was the summit if it weren’t for the sign), and we decided the cloud patterns weren’t threatening enough to abort the mission.

After the summit of Flattop was the longest and most serene walk over alpine tundra that I can remember. For four miles, we didn’t see another human or animal. The trail became a 3-inch stream running with snowmelt. As we descended, we came upon a gang of elk, who saw us and suspiciously retreated downhill. It’s a different world on the west side of the Park — elk on the Estes Park side are well-accustomed to having their photos taken by crowds of humans.

(photo by Syd Jones)

Around Mile 23, as we descended the trail next to Tonahutu Creek, the mosquitoes began to attack. I felt bad about talking Steph into accompanying us, as she swatted at the 50th mosquito to bite her exposed shins, and the three of us robotically plodded downhill in silence. I fantasized about the moment I would see the car piloted by Syd’s wife, Debi, at the 25.5-mile mark, and tried to wish the trailhead closer.

I felt we were on a treadmill for the last three hours, and after our last turn, onto the Green Mountain Trail, Syd and I slowed to a 2 mph pace on sore feet. Then, at last, I thought I heard a car drive past. A few dozen steps later, we could see the color of Debi’s car in the dying summer light. The three of us collapsed into the car seats, and nodded off to sleep as Debi navigated the curves in the road all the way back to Denver.

All told, the hike is 25.5 miles, with 5,200 feet of cumulative elevation gain, starting at the Longs Peak trailhead at 9,500 feet, crosses one 12,000-foot pass, descends to 9,000 feet, and climbs again to the summit of 12,324-foot Flattop Mountain, before descending back to the 8,800-foot Green Mountain Trailhead. It’s a stout undertaking for the average weekend warrior, but doable by anyone who spends a lot of time running or hiking. And eating nachos in a bar thinking up crazy ideas.

To do the whole hike in a day, here’s what you’ll need:

  1. An early start. We were at the Longs Peak trailhead at 4 a.m.
  2. Someone to pick you up at the Green Mountain trailhead on the other side of the park, a 4-hour drive from the Longs Peak trailhead.
  3. Good weather. At the top of Flattop Mountain, you’ll have to make a decision on the weather. If it looks like a thunderstorm is rolling in, it’s time to bail and hike back down to the Bear Lake trailhead. Continuing the hike west from the top of Flattop in bad weather would be treacherous — you still have miles of walking in completely exposed terrain before you get below treeline again.
  4. Water treatment supplies — Iodine, water filter, SteriPen, etc. Your last real water source on the hike, before you get to Tonahutu Creek at about the 18.5-mile mark, is Bear Lake, at approximately 11.5 miles.
  5. The 10 Essentials. The hike is 25.5 miles, and you’re never more than 7.1 miles from a trailhead, but most of the hike is above treeline and exposed to the elements.
  6. A camera.
  7. Some good old-fashioned stick-to-it-iveness.


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