Mt. Whitney lies on the boundary of Sequoia National Park and Inyo National Forest. Most people who climb Mt. Whitney start from the east side of the Sierra and remain in Inyo National Forest throughout their hike. Because it is the most frequently climbed mountain peak in the Sierra Nevada, a permit system is in place to minimize the impact of day-hikers on the Mt. Whitney backcountry. All hikers entering the Mt. Whitney zone, including day-hikers, are required to obtain a permit.