The trail's official length is 338.6km, although the walk out from Mount Whitney adds another 18km to the total. From its northern terminus in Yosemite Valley, the trail runs northeast, passing south of Half Dome and then on to Tuolumne Meadows. From Tuolumne Meadows the trail turns south, running parallel to the main range of the Sierra Nevada, through Yosemite National Park, Inyo and Sierra national forests (including the John Muir Wilderness and Ansel Adams Wilderness), passing through Devils Postpile National Monument, Kings Canyon National Park, and ending on Mount Whitney in Sequoia National Park. It is estimated that, when hiking from north to south, the amount of ascent of the trail is just over 14,000m and the total descent is just over 12,000m.

When we arrived in California, we took a bus to Merced, and then met one of the biggest challenges of the trip because no-one we asked knew how to get to a supermarket on foot. After hours of asking we eventually found one that we could actually walk to, bought food and a large storage bucket from a hardware store, filled it with supplies and posted it to Vermillion Valley Resort including some dried food that we had brought with us from Hong Kong. The intention was to carry 3 or 4 days of food and stop at Tuolumne Meadows and then Reds Meadows, before carrying 10 days of food for the rest of the trip. 

Once we arrived at Happy Isles and reached the Ranger's centre, we rented two polycarbonate bear barrels, packed one of them with food, the other with clothes, and almost immediately started walking. We would have to post back the bear barrels from Lone Pine at the end of our walk. Isabelle's bag was almost entirely taken up with the two barrels, while I carried everything else. Neither bag was light, and we were aware that with 10 days of food to carry after Vermillion Valley, we would need to get stronger and fitter.