25-Year-Old Mountaineer Simon Kearns Shatters Mount Rainier Unsupported Round-Trip Speed Record by 31 Minutes

The landscape of high-altitude endurance sports saw a significant shift on May 9, 2026, when 25-year-old mountaineer and professional guide Simon Kearns established a new benchmark on Mount Rainier. Kearns, a guide for Rainier Mountaineering Inc. (RMI), completed the 14.5-mile round-trip journey from the Paradise parking lot to the 14,411-foot summit and back in a staggering 3 hours, 43 minutes, and 52 seconds. This performance did not merely edge out the previous record; it redefined the possibilities for on-foot travel on the mountain, lopping more than 30 minutes off the standing unsupported record.

The previous record, set by Alex King in June 2021, stood at 4 hours, 14 minutes, and 13 seconds. Kearns’ achievement represents an approximately 12% improvement over the former fastest known time (FKT), a margin rarely seen in established endurance corridors. Covering roughly 9,000 feet of vertical gain at high altitude, Kearns’ effort required an average pace that accounts for both the aerobic strain of the ascent and the technical precision required for a safe, rapid descent across glacial terrain.

The Evolution of the Attempt: From Skis to Microspikes

The record-breaking run was not Kearns’ original objective for the 2026 spring season. An accomplished skier, Kearns had initially spent months training to challenge the ski-ascent and descent record. However, a combination of environmental factors and equipment failure forced a tactical pivot. The Pacific Northwest experienced a notably lean snow year, resulting in what meteorologists and hydrologists categorize as a "snow drought." This lack of deep pack made several traditional ski lines technical or impassable.

The final catalyst for the change in plans occurred just one week before the attempt when Kearns snapped his only pair of race skis during a training session. Faced with the choice of abandoning the season’s goals or adapting to the conditions, Kearns opted to transition to an on-foot, "running" attempt. This decision necessitated a shift in training focus, moving from the specific mechanics of skinning and downhill transitions to the high-cadence demands of mountain running on snow and ice.

Technical Execution and the "Unsupported" Standard

In the world of FKTs, the "unsupported" designation is the most rigorous category. It dictates that the athlete must carry all necessary supplies from start to finish, with no pre-placed caches, no pacing from other runners, and no outside assistance of any kind. Kearns’ kit was a study in minimalist efficiency, balancing the need for speed with the mandatory safety requirements of a solo glacier crossing.

His equipment included:

• Lightweight trail running shoes equipped with microspikes for traction on frozen corn snow and glacial ice.
• A minimalist crevasse rescue kit, essential for solo travel on a mountain known for its volatile glacial architecture.
• Collapsible ski poles to assist with stability and rhythm during the 4,500-foot-per-hour ascent.
• A lightweight helmet and essential thermal layers to mitigate the risks of Rainier’s unpredictable summit weather.
• Emergency supplies and basic nutrition/hydration carried in a streamlined running vest.

The route followed the most common line for speed attempts, beginning at the Paradise parking lot (5,400 feet). From there, Kearns ascended the Muir Snowfield to Camp Muir (10,188 feet), a standard high camp for guided parties. Beyond Muir, the route became significantly more technical, traversing Cathedral Gap and ascending the Ingraham Direct. At this time of year, the Ingraham Direct provides a more linear path to the summit crater than the Disappointment Cleaver, though it remains exposed to objective hazards such as serac falls and hidden crevasses.

A Chronology of Performance

Kearns’ ascent was characterized by a relentless pace that saw him reach the summit well ahead of his own optimistic projections. Upon reaching the 14,411-foot apex, he transitioned immediately to the descent, navigating the steep, snowy slopes with a combination of glissading and high-speed running.

The physical toll of such an effort is immense. Upon returning to the Paradise parking lot and confirming his time, Kearns described a sense of overwhelming relief and disbelief. The 31-minute margin indicated that he had found a "flow state" rarely achieved on such technical terrain. For Kearns, the success was the culmination of 13 years of mountaineering experience, having begun his training as a guide and climber at the age of 12.

Historical Context of Rainier Speed Records

Mount Rainier has long served as the premier testing ground for American mountaineers. The history of speed records on the peak dates back to the mid-20th century and is deeply intertwined with the history of Rainier Mountaineering Inc.

The first documented speed record was established in 1959 by RMI founders Lou and Jim Whittaker, along with John Day. Their time of 7 hours and 20 minutes was considered revolutionary for its era, proving that the mountain could be climbed and descended in a single day by those with elite conditioning. Over the subsequent decades, the record has been chipped away by a lineage of guides and elite athletes who utilize their "days off" to test their limits.

The "guide’s advantage" is a recognized phenomenon on Rainier. Professional guides, such as Kearns, spend hundreds of hours on the mountain each season, gaining an intimate knowledge of the route’s shifting crevasses, snow consistency, and weather patterns. This institutional knowledge allows them to identify the precise window when the snow is firm enough for fast travel but not so icy as to be treacherous.

Profile of an Elite Guide: Simon Kearns

A native of San Juan, Colorado, Kearns transitioned to the Pacific Northwest to further his career in professional guiding. Since joining RMI in 2025, he has summited Mount Rainier 15 times, including a previous "car-to-car" best time of 4 hours and 18 minutes. His resume extends far beyond the borders of Washington State, reflecting a versatile athlete capable of performing across different disciplines and geographies:

• Colorado 14ers: Kearns has summited 33 of Colorado’s 58 peaks over 14,000 feet.
• Regional FKTs: He holds current speed records on Mount Hood (Oregon) and Mount Massive (Colorado).
• International Experience: Summits of Mont Blanc in the French Alps and the Grand Teton in Wyoming.
• Recent Performance: Just days before his Rainier record, Kearns set a new FKT on Mailbox Peak, a notorious training ground for Seattle-area climbers.

Broader Implications and Future Aspirations

The success of Kearns’ run highlights a growing trend in mountaineering where the lines between traditional climbing and mountain running are increasingly blurred. As equipment becomes lighter and more specialized, athletes are able to move through technical terrain at speeds that were previously thought impossible.

However, experts note that such records are highly dependent on environmental conditions. The "snow drought" of 2026, while detrimental to the skiing community, created a unique window for on-foot travel. Hard-packed snow early in the season can act as a "pavement," allowing runners to maintain a high cadence that would be impossible in the post-hole conditions of a heavier snow year or the loose scree of late summer.

Looking forward, Kearns has indicated that his primary focus remains his professional responsibilities as a guide, helping clients navigate the same slopes he recently conquered at record speeds. Nevertheless, his competitive drive remains active. He has identified Longs Peak, a 14,259-foot mountain in Colorado’s Rocky Mountain National Park, as his next major FKT target.

As the "Fastest Known Time" community continues to grow, Kearns’ 3:43:52 mark on Rainier stands as one of the most significant achievements in the sport’s recent history. It serves as a testament to the efficacy of long-term athletic development, the ability to adapt to changing environmental conditions, and the enduring legacy of the mountain guides who call Mount Rainier their office. For now, the mountaineering world watches to see how long this new benchmark will stand before the next generation of athletes attempts to shave seconds off the 25-year-old’s historic time.