from the GetOutdoors site.

Mt. Whitney draws the most climbers of any mountain in the United States. Approaches from the east side are more common, but the western approach is also popular. The western approach is more committing, so be prepared for a longer, but perhaps more rewarding hike.

Climbing Mt. Whitney
Mt. Whitney is the most frequently climbed peak in the Sierra Nevada, if not in the US. Because of this a permit system has been implemented 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.

1. Whitney Portal: Mt. Whitney can be most directly reached by a 10.7 mile (17.1 km) trail from Whitney Portal, 13 miles (21 km) west of the town of Lone Pine on the east side of the Sierra. Ice axes and crampons are needed in spring and early summer, but technical climbing equipment is not usually necessary between mid-July and early October. The elevation at the trailhead is 8360'' (2550 meters). The elevation at the summit is 14,495'' (4417 meters).
   • Permits for this trailhead must be obtained through the Inyo National Forest. If you are interested in going to Mt. Whitney from Whitney Portal, contact the Mt. Whitney Ranger District, PO Box 8, Lone Pine, CA 93545, 619-876-6200, for additional information.
2. Other Trailheads: There are other routes besides Whitney Portal from which to reach Mt. Whitney. These leave from less heavily-used trailheads, but require a longer hike to reach the summit. The High Sierra Trail leaves from Giant Forest on the west side of Sequoia National Park, and takes a minimum of 6 days (shuttle trip) or 10 days (round trip) to complete. Only seasoned hikers with good trail experience and in first-class physical condition should take this trip.
   • Backcountry permits for the High Sierra Trail from Giant Forest are issued at the Lodgepole Visitor Center''s backcountry office. Permits are required for all overnight hikes in Sequoia National Park. Permits may be reserved no later than 3 weeks before the start of your trip. Even if you have reserved a permit, you must still check in at Lodgepole prior to starting on your trip.

Day 1 - to Bearpaw Meadow (11.4 miles/18.2 km):The trail leaves from Crescent Meadow on the southeast edge of the Giant Forest. For the first half-mile, the trail travels through shady, well-watered terrain covered with dense forests of red and white fir, sugar pines, and occasional giant sequoias. The trail then emerges onto a warm, south-facing slope at Eagle View. From here, you can see back to Moro Rock to the west, down to the Middle Fork of the Kaweah River, and ahead to the glaciated peaks of the Great Western Divide. The nearly-level trail then passes through part of the area burned by the Buckeye Fire in 1980. Spring-fed streams cross the trail late into the season.

Beyond the junction with the Seven Mile Hill Trail, which connects the High Sierra and Alta Trails, the trail crosses the steep slopes and bluffs of the south side of Alta Meadow and Alta Peak.

Hikers taking a more leisurely trek to Mt. Whitney may wish to camp along one of the two forks of Nine Mile Creek (8.8 miles/14.1 km). After passing Nine Mile Creek, the trail descends to Buck Canyon, a spectacular canyon well-known for floods, avalanches and rockslides. The Buck Creek crossing may be hazardous early in the summer. Be sure to check on the conditions here when you pick up your permit. After crossing Buck Creek, the trail climbs some 500'' in slightly over a mile (152 meters in 1.6 km), arriving at the Bearpaw Meadow area 11.4 miles (18.2 km) from the trailhead.

Day 2 - to Big Arroyo Junction (11 miles/17.6 km): East of Bearpaw, you begin your ascent into the Great Western Divide. After passing some nice campsites at Lone Pine Creek (13.1 miles/21.0 km from the trailhead), the trail follows a long series of switchbacks, overshadowed by the Angel Wings, a sheer granite wall to the north of the trail. The route crosses Hamilton Creek just above the lower Hamilton Falls and climbs another series of switchbacks to Big Hamilton Lake (16.6 miles/26.6 km). The popular campsites here offer outstanding views and fair to good fishing for brook, rainbow and golden trout.

Beyond Big Hamilton Lake, there is nowhere to go but up! The climb begins with a series of sweeping switchbacks across the bluffs to the north of the lake, before turning east towards the sheer-walled avalanche chute known as Hamilton Gorge.

East of Hamilton Gorge, the trail enters the alpine life zone of the Sierras. Precipice Lake, which is nestled beneath the north wall of Eagle Scout Peak, often stays frozen into mid-summer. Beyond the lake, the route passes a series of shallow glacial ponds, to finally arrive at Kaweah Gap on the Great Western Divide (20 miles/32 km). From this pass at 10,700'' (3261 meters) it is only a few hundred vertical feet down to the open valley of the Big Arroyo. The trail continues a steady to moderate descent to the campsites at Big Arroyo Junction (22.5 miles/36 km).

Day 3 - to Moraine Lake (8 miles/12.8 km) or Upper Funston Meadow (12 miles/19.2 km): After 2 strenuous days of hiking, the journey from Big Arroyo to Moraine Lake is relatively easy. If you have a tighter schedule, you may wish to bypass Moraine Lake, an extra .8 miles (1.3 km), and proceed directly to Upper Funston Meadow, at the bottom of the Kern Trench.

After leaving Big Arroyo Junction, the trail makes a moderate ascent up the north wall of the Big Arroyo, providing views of the east side of the Great Western Divide. Once it reaches the Chagoopa Plateau, the trail levels off, and soon reaches a junction on a tributary of Chagoopa Creek. The right-hand trail branches off from the main High Sierra Trail to Moraine Lake (30 miles/48 km from Crescent Meadow). The left-hand trail follows a more direct route across the Chagoopa Plateau, rejoining the Moraine Lake Trail at Sky Parlor Meadow (30.8 miles/49.3 km). From here, it descends to the bottom of the Kern Trench. The drop is moderate at first, but concludes with a series of steep, rocky switchbacks. This stretch of the trail can be long and dry, so be sure to fill your water bottles at Sky Parlor Meadow. To reach Upper Funston Meadow (34.5 miles/55.2 km), turn south (right) upon reaching the bottom of the canyon.

Day 4 - to Junction Meadow (13.7 miles/21.9 km from Moraine Lake/9.7 miles; 15.5 km from Upper Funston): If you are coming from Moraine Lake, continue about 1 mile (1.6 km) beyond the lake to rejoin the High Sierra Trail at Sky Parlor Meadow. Descend into the Kern Trench, but turn north (left) upon reaching the bottom. If you are coming from Upper Funston, retrace your steps to the junction with the trail from the Chagoopa plateau, and continue north along the bottom of the canyon.

The Kern River Trail drops into a marshy area beyond the junction, then leads through a forest of Jeffrey pine and incense-cedar. Keep an eye through the trees to the west to catch a glimpse of Chagoopa Falls tumbling down from the rim of the canyon. At 36.8 miles/58.9 km from the trailhead, you will arrive at Kern Hot Springs, complete with a crude cement bathtub in which to soak your aching muscles. The water from the spring is 115 degree F (46 degrees C). The tub is only a few feet from the cold, rushing Kern River, and runoff from the tub mixes with river water to create a warm pool. (Please, no soap in the river or tub.)

Beyond Kern Hot Spring, the trail continues along the bottom of the glaciated valley of the Kern River. This canyon runs almost due north and south for about 25 miles (40 km) along the Kern Canyon fault. The trail ascends steadily to Junction Meadow (42 miles/67.2 km). Hiking along the bottom of the canyon can be hot and dry during the middle of the day. If you have camped at Kern Hot Springs, however, remember that cold air from the surrounding peaks flows down the canyon at night, and that the sun will not clear the 2000 to 5000'' (610 to 1524 meter) high canyon walls until relatively late in the morning.Day 5 - to Crabtree Meadow (8.9 miles/14.2 km): Leave the park-like Jeffrey pines of Junction Meadow and cross a steep, rocky slope covered with manzanita and currant. Soon, the trail begins to climb out of the Kern Canyon, offering increasingly impressive views of the canyon to the south, and west to the Kaweah Peaks. At 48.9 miles from the trailhead (78.2 km), you will reach the junction with the John Muir Trail. There are campsites here, as well as at Crabtree Meadow (53.1 miles/85 km). Guitar Lake (56.6 miles/90.6 km) is the last campsite with water before the summit of Mt. Whitney.

Day 6 - to the summit of Mt. Whitney: If you have arranged for transportation from Whitney Portal and this is the last day of your trip, this will be a long day (19.1 miles/30.6 km). You may also camp at Trail Camp (65.7 miles/105.1 km from the trailhead) or Outpost Camp (68.7 miles/109.9 km) on the east side. If you are hiking back to Giant Forest, plan to return to Crabtree Meadow (round trip to the summit, 16.8 miles/26.8 km).

The final climb begins with a moderate traverse along the "back" side of Mt. Whitney; then the trail begins its switchbacking climb to Trail Crest, the divide between the west and east sides of the Sierras. Fill your water bottles before starting on this climb; there is no reliable water supply between Guitar Lake and Trail Camp on the east side. A hundred yards (91 meters) below Trail Crest, you will find the 2.4 mile (3.8 km) spur trail to the summit of Mt. Whitney. If you wish to leave your backpack at this junction while you make the climb to the summit, be sure your food is secure from the hungry marmots who frequent this area. The trail to the summit follows an open, rocky route along the west side of the Sierra crest. The windswept, barren summit of Mt. Whitney is home to hardy flocks of rosy finches(please do not feed the animals).

The Mount Whitney Hut was built at the summit in 1909 as a station for meteorological observations. The metal roof of this hut attracts lightning which can be conducted through the building to individuals inside. Do not seek shelter here during a storm. Check the weather conditions before beginning the hike to the summit.

After returning to Trail Crest, hikers heading out to Whitney Portal will descend 100 switchbacks to Trail Camp, a popular camping area for hikers coming from the east side. If you keep going, the rocky trail follows Lone Pine Creek down to Mirror Lake, a glacial cirque that is closed to camping, then continues along the creek to Outpost Camp, the last camping before Whitney Portal.

Day 7 (if returning to Giant Forest) - to Kern Hot Springs (14.5 miles/23.2 km) or Upper Funston Meadow (18.5 mi./29.6 km): Retrace your previous route.

Day 8 - to Big Arroyo (12 miles/19.2 km from Kern Hot Springs; 8 miles/12.8 km from Upper Funston): Retrace your previous route.

Day 9 - Explore Nine Lakes Basin and return via Kaweah Gap to Hamilton Lakes (4.8 miles/7.7 km plus side trip): An unmarked trail leaves the High Sierra Trail at the point where it turns west and begins the climb up the east side of Kaweah Gap. Follow this unmarked trail north if you wish to take a side trip to the Nine Lakes Basin. If you plan to hike in this or any off-trail area, always carry a topo map and compass, and be sure you know how to use them.

Day 10 - to Crescent Meadow via the High Sierra Trail (15.5 miles/25 km): Retrace your previous route.