The Alpine Trail is broken into two parts, a north section and south section. The middle section is separated by the Jewel Basin hiking area.
The southern section of Alpine Trail (described here) is a solid 20+ mile trail with more descending than climbing. Despite the loss in elevation, there are sections of climbing and some exposure, so it is for those who have the fitness and confidence to tackle such a trail.
The southern half begins at Napa Lookout #31 and climbs to Inspiration Pass. From there, it follows the ridge above timberline north across high alpine meadows, passing Warrior Peak, Gildart Peak, and Thunderbolt Mountain. The views across the rugged and rocky ridgelines are endless as you travel across the sky before eventually descending to the town of Swan Lake.
Depending on what you want to bite off in a hike, you can make connections with (in order from south to north): Wire Trail, Bond Creek #21, Hall Lake #61 or Sixmile Lookout.