This is a long-distance day hike that includes unmaintained trails. To hike this route, you should be both an experienced route finder willing to hike trails less traveled and prepared for a lonely hike. You may need crampons and an ice axe well into July.
Why go? To condition yourself for long miles with significant elevation changes, to experience the difficulty of the Cascade Crest Trail before there was a Kendall Katwalk, or just to see new views.
Begin by hiking to Snow Lake. Continue past the camps on the east side of the lake, and at 3.3 miles and 4,100 feet, encounter a junction with signs to Gem Lake (left) and Middle Fork Road (right). Go right, on what is more accurately the Rock Creek Trail. The trail quickly narrows and becomes rockier, while puddles and squishy mudholes may linger even in dry weather. The trail drops steadily and steeply across talus (especially the middle section, often overgrown with a fern "forest") and through (real) forest for 3.5 miles and almost 2,400 feet. Along the way is a seldom-seen view of Rock Creek, tumbling down a lengthy rock face after its exit from Snow Lake.
At 6.8 miles, arrive at a junction with the Middle Fork Trail (#1003) and take a right. This section of trail follows an old road, gaining less than 150 feet of elevation over the next 3 miles. Water is available at Thunder Creek, 1 mile later at an unnamed creek and at Burntboot Creek. Camping is possible near Thunder Creek at 7.8 miles.
There is NO water source on the entire climb once you leave Burntboot Creek. A snowpatch lingers well into August near the top, and there is standing water (not an ideal water source) in Red Pond eventually. Make sure you have plenty of water as you begin your climb, especially on a hot day.
The key to successfully completing this hike is finding the faint, unsigned trail that leaves the Middle Fork Trail for Red Pass. 9 miles into your hike, you get to Burntboot Creek. The three-log crossing of Burntboot Creek, which led to the Goldmyer Hot Springs property, washed away several years ago. There is a tree with a sign for "Burntboot Creek." The trail follows Burntboot Creek upstream for about 100 ft, then descends to the creek bed. There are multiple faint trails that go further upstream along Burntboot Creek, in the forest. It meanders along the creek, then drifts away. 400 feet from the Burntboot Creek sign is proof that you are on the right trail: two signs on a tree, one forbidding bicycles (this sign actually fell off the tree and sits at the bottom of the tree) and the other reading "trail not maintained beyond this point."
Once you are at this tree, the trail is obvious and shortly after starts climbing. It climbs moderately steeply through lovely old-growth forest. It seems like an endless set of switchbacks as you gain 3,500 feet in just over 3 miles. This part of the trail may have blowdowns when not actively maintained. Enjoy the shade for the first 2 miles, then break out into views seldom seen.
At 12 miles from the Snow Lake trailhead, crest over a small pass to an intimidating view of the steep chute leading up to Red Pass. This chute is the only way up to Red Pass other than 5th-class rock. When the snow is melted, switchbacks make this an easy ascent. This steep northeast-facing gully is filled with icy snow well into July. Crampons and an ice axe are often necessary to safely ascend to the pass. It's only 200 vertical feet of ascent, but in June or early July, this is more technically difficult than what you would typically find on the standard routes of any of Washington's volcanoes (not counting crevasse crossings). Know conditions before you go, and don't be afraid to turn around if conditions become dangerous.
At Red Pass, located at 12.4 miles and 5,337 feet, going right is a spur trail towards Lundin; taking the trail to the left, you follow the ridge for 0.1 mile before descending a rocky trail down to the plateau holding Red Pond. From there, steep switchbacks take you down into the Commonwealth basin. Drop to 3,875 feet, where your next water stop is available, just under 14 miles from your starting point.
At 14.3 miles, go right, where a broken sign on a tree reads "Abandoned." At 14.5 miles, rock-hop or ford Commonwealth Creek, then cross again on a log bridge at 14.7 miles. At 14.9 miles, take the short side trail to a worthwhile view of a waterfall. Continue down the narrow and brushy trail to connect with the Pacific Crest Trail, then go right the final 100 yards to arrive at the Snoqualmie Pass trailhead. To close the loop, walk pavement downhill to Alpental Road, then right to retrace the driving route to the Alpental parking lot, a total of 1.5 pavement miles.