Guides Page

Yosemite National Park guides have decades of experience to lend to your adventure. Yosemite Mountaineering School guides are your ticket to exploring the park's backcountry. We offer rock climbing, hiking, and backpacking during the warmer months and backcountry ski tours in the winter. Meet some of our guides below.

Yosemite Mountaineering School and Guide Service
Dave Bengston	YMS Director, guide since 1985. AMGA Rock Certified Guide. Leave No Trace Master Certified. Extensive skiing and alpine climbing experience. Big wall guide with 48 ascents of El Capitan, many speed records. Numerous first ascents in Yosemite Valley, Tuolumne Meadows, and Joshua Tree, up to 5.13 and including Kaos, El Capitan. BS Physics.
Bradley Gasawski	YMS Assistant Manager. Bradley is a PSIA certified Alpine, Telemark and Nordic Ski Instructor. He is a Certified Interpretive Guide through the National Association of Interpretation, a Leave No Trace Trainer, Level I Avalanche Certified and Wilderness First Responder. Before coming to Yosemite, Bradley earned an M.S. in Recreation Administration. He enjoys teaching people new things and sharing his passion for the outdoors with others. When not working, you can find him playing outside.
Climbing Guides
Bill Russell	YMS climbing guide since 1993; began guiding in 1983. Veteran of Yosemite big wall first ascents, desert towers and many alpine ascents. Guides in Red Rocks, NV during the winter. Previous Yosemite Search and Rescue Team member. Previous Professional Ski Patrol member.
Scott Stowe	YMS climbing guide since 1995. Part of the "Dream Team" speed wall climbers. Over 70 ascents of El Capitan, including 2 first ascents; Reticent Wall & Every Man For Himself. Climbing since 1984.
Kevin Sesler	YMS climbing guide since 1998. 17 El Cap ascents. Active in Yosemite Search and Rescue. Extensive free climbing in the US, Europe, Mexico and Asia. Spanish speaker. Leave No Trace Trainer Certified. Guides in Red Rocks, NV during the winter. BS Resource Management.
Josh Helling	YMS guide since 1993. Certified AMGA rock guide, certified PSIA Nordic ski instructor, Rigging For Rescue certified. More than 26 ascents of El Capitan, and 70+ big wall climbs. 1st ascent big wall expedition climbs in Greenland, Baffin Island, Antarctica, Morocco, & Socotra Island Yemen. Many alpine ascents, and ice climbs. Professional photographer, videographer, and film rigger. Active member of Yosemite Search & Rescue.
Jeff Scheuerell	YMS climbing guide since 2001. Extensive Yosemite climbing experience, with 30 first ascents. Has been climbing since 1985. 22 years climbing experience. Guided caving in Sequoia National Park for 5 years prior to joining YMS. Wilderness First Responder. BS Resource Recreation, with minor in Outdoor Leadership.
Constantine Severis	YMS climbing guide since 2003. AMGA Certified Rock Guide. Ski patroller in CO in winter. Has guided in Telluride, CO, Red Rocks, NV and Mt. McKinley in AK. Guided a sucessful ascent of Mt. Everest.
Hope Wolf	YMS climbing guide since 2003. APP Certified Ski Patroller. Wilderness EMT certified. Sonora Pass Highway climbing guidebook author. Climbing since 1980. Leave No Trace Trainer Certified.
Chris Ecklund	YMS climbing guide since 2005. Rock and alpine guiding in the Sierra Nevada since 1998. AMGA certified Rock Guide.
Dave Lane	YMS guide since 2006. AMGA Certified Rock Guide. Climbing for 16 years with 6 El Cap ascents, first ascents in the High Sierra and Deserts of the Southern California. AIARE Avalanche instructor. Climbed in Spain, Mexico and Greece.
Nate Kerr	YMS climbing guide since 2007. AMGA Certified Rock Guide. Former Pacific Crest Outward Bound School Instructor, avid climber and backcountry skier, pursuing further AMGA certification. Yosemite Cross-Country ski guide.
Doug Nidever	YMS Guide since 1984. IFMGA certified guide. Started climbing in 1968. Multiple ascents of Yosemite's big walls and extensive Tuolumne experience. Alpine Guide and Ski Guide on the Eastern High Sierra during the winter. Father of Tobin and Layton. Owner of Nidever Mountain Guides.
Mark Grundon	YMS guide since 2009. AMGA Certified Rock Guide. Mark has been climbing for 12 years and has 5 El Cap ascents. He has guided in Colorado, Alaska, Mexico, and Nepal. Mark is a strong believer in “living the dream”, and following your passions whatever they may be. He currently guides in El Potrero Chico in Mexico in the winter. Mark also has an EMT certification, a Leave No Trace Trainer certification, and a B.A. in Recreation and Environmental Studies.
Aaron Jones	Climbing since 2001, in Yosemite since 2003. 40 ascents of El Capitan and over 70+ big wall ascents. Solo ascents of Nose on El Cap in 20 hours and Zodiac route in under 13 hours. Extensive alpine experience including solo ascents of Torres del Paine in Chile. AMGA Rock Instructor and pursing AMGA Rock Guide certification.
Lyra Pierotti	Lyra had her first view of the mountains atop the shoulders of the Tahoe Summer Music Festival's tuba player, back when she weighed less than a tuba. This exposure led her to study ecology and pursue rock climbing. While studying at UC San Diego, she worked as a guide for her university’s outdoor program, leading rock climbing, backpacking, and sea kayaking trips, and taught field ecology for several San Diego-based outdoor education programs. Lyra spent a year living in the French Alps, studying geology, climbing, and skiing. She has been based out of Bishop since fall 2008, and has worked as a guide throughout the Sierra Nevada, on Mt. Shasta, and on the high altitude volcanoes of Mexico. Lyra holds a Wilderness First Responder certification, has completed her Level 2 AIARE Avalanche course, and passed the AMGA Rock Guide Course/Aspirant Exam. She aims to be an AMGA Certified Rock Guide this fall, and looks forward to continuing her higher education in the mountains through the AMGA Guide Training Program.
Hiking Guides
Joe Link	Joe has been a hiking and backpacking guide since 2004. He is a former Search and Rescue team member, Wilderness First Responder certified, Leave No Trace Trainer Certified and a Certified Interpretive Guide through the National Association of Interpretation. Joe earned a B.S. in Park Management from Unity College in Maine.
Josh McClure	YMS hiking and backpacking guide since 2006, extensive climbing, hiking and backpacking experience at National and International destinations, including the Himalayas. B.S. Natural Resources Management. Certified Interpretive Guide through National Association of Interpretation.
George Ridgley	30 years hiking, climbing, and backpacking in Yosemite.
Joel Fluty	Hiking guide since the summer of 2008. Wilderness First Responder, Certified Interpretive Guide through the National Association of Interpretation. Joel has many years of experience in the outdoors both nationally and internationally.
Zach Irwin	Zach started working with the Yosemite Mountaineering School teaching Nordc ski classes and leading winter trips in December of 2010 and he stayed with us for the summer season. Zach has hiked and worked in Colorado and Swizterland. Zach earned a Bachelors Degree in Recreation, Parks & Tourism Management from Penn. State. Zach loves Yosemite and enjoys sharing his passion wth you.
Julie Sanderson	Julie has been a hiking guide at YMS since 2010. Before that she earned her BS in Outdoor Education and Leadership. Julie has spent years leading teenagers on backpacking trips and working in wilderness therapy. She also is a PSIA certified Alpine, Snowboard, and Telemark instructor. She has her Wilderness First Responder, and is a Leave No Trace trainer. Julie loves spending time in the wilderness and enjoys sharing its beauty with others.
Sarah Martin	Sarah has been a hiking guide since 2010. She earned a B.S. in Psychology and is Wilderness First Responder certified. Sarah has worked in Hawaii as a Trip Leader for high school students as well as kayak guide in Yellowstone.
Cross Country Ski Guides
Rick Stockwell	PSIA certified Nordic ski instructor and Yosemite Cross Country ski guide. XC and Mountain School guide since 1980. Backcountry skiing, hiking and backpacking guide and expert snow camping and survival instructor.