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Experience Level



10-12 miles/day


8,600-11,000 feet

Registration Fee


Program Overview: Enjoy a rare opportunity to hike at high elevations off trail and above the tree line to the Lyell glacial basin, located below the slopes of Yosemite’s highest peak to explore the glacial ice body that was once a living glacier. Your reward for scrambling over uneven terrain and braving strong wind and sun at high elevation will be to see the body of this recently living glacier before it is gone!

Explore the past, present, and future of what was once Yosemite’s largest glacier as well as the geology of the Sierra Nevada during this unforgettable adventure with experienced Yosemite naturalists. During this trip you will see firsthand the evidence of past glaciation in this area such as glacial erratics, striations, and polish. You will clearly see relatively young moraines formed by the Lyell glacier. Yosemite’s geologic story is something extraordinary, and on this trip, you’ll get a taste of its unique story!

To allow for acclimatization on this trip, there is an optional day hike on Thursday before setting off up Lyell Canyon on Friday morning. Spending two nights and a day at elevation will really help when we start fully loaded up the trail. For your acclimatization hike on Thursday, we’ll plan to meet at Tioga Pass at nearly 10,000 ft elevation and explore from there towards the Gaylor Lakes Basin. Your naturalist guide will share with you about this stunning area, and dive into the science behind Yosemite’s changing climate: how it impacts not only California, but the world.

On Friday, you’ll be ready to take in the sights of Lyell Canyon while hiking ten miles on the relatively flat John Muir Trail before setting up camp for two nights in the forest before you reach Lyell Basin. On Saturday, you’ll break into two groups and brave an off-trail ascent to get close to the ice body. This off trail terrain has difficult footing with loose rocks and boulders while moving uphill at high elevation. It’s important everyone is physically fit for this hike and has good balance. After an exciting day of learning about geology and climate change, return to camp for a restful night before hiking out the same trail on Sunday.

Know Before You Go:

  • Program dates: Thursday, August 31, 9am-3pm day hike (optional for acclimatization) and evening meeting 7:30pm-9pm. Start hike at 8am Friday, September 1 and exit Sunday, September 3 by 5pm.
  • Program location: The Thursday acclimatization hike will go to Gaylor Lakes. The three-day backpack will take the John Muir Trail 10 miles south through Lyell Canyon.
  • What’s included: An optional day hike for acclimatization, an evening meeting, and three full days of guided instruction by a Yosemite Naturalist Guide, park entry (as needed), and shared tent camping (camping dates cannot be altered). There is no discount if you choose not to use the included gate pass or campsite.
  • Camping dates: Participants can arrive on August 30 after 12pm and depart September 1 by 11am. After the backpack, participants can arrive on September 3 after 12pm and depart, September 4 by 11am. There are three shared campsites among all the participants. We guarantee tent camping only. If you choose to bring a recreational vehicle, we cannot guarantee you will have a parking spot. Please be prepared to tent camp. A picnic table, bear locker and firepit are provided at each site. Campsites fit 6 people per site.
  • Campground Location: White Wolf
  • Lodging: Upgrade to Tuolumne Meadows Lodge for an additional fee. Lodging dates match camping dates. Lodging blocks expire 30 days prior to the program. Details on using our Group Code will be emailed to you immediately after registering.
  • Experience level: Participants must have prior backpacking experience, be physically fit, and be prepared for a strenuous 25-30 mile roundtrip hike at high elevations reaching 11,000′. We recommend training in advance by hiking up hills or stairs while carrying a heavy pack.

What’s not included:

  • Gear or meals during your program.
  • Camping gear or meals in the shared campsites.
  • Transportation.

View a suggested packing list including gear rental options.