We started from the Highway 21 trailhead and hiked 4.5 miles to our turnaround point on a hilltop looking east, which made a scenic picnic spot.  Along much of the hike there were expansive views of gently-contoured mountains and gorgeous wildflowers blooming later than usual due to the cool and wet spring. We kept an eye out for rattlesnakes, but fortunately saw only a harmless, though good-sized, garter snake at one of the creek crossings. We were glad we'd gotten an early start because by mid-morning it was hot and our last mile outbound was fairly exposed. We encountered only one other group of hikers, who were camping just before our turnaround and reported there was a spring nearby. Thirteenmile is included in Craig Romano's "100 Classic Hikes Washington," and although we only did a portion of the entire 16-mile trail, we felt it earned its place for the profusion of wildflowers and lovely views. 

I camped the night before at Ten Mile Campground, which is about three miles north of the Thirteen Mile Trailhead on Highway 21. Wanted to summit Seventeen Mile Mountain, which required about a 30-mile out and back day hike. Started my hike at 5:45 am. 

The trail climbs moderately as it skirts a big canyon, at the bottom of which flows Thirteen Mile Creek. Old growth Ponderosa and Douglas Fir are frequent in this open forest. The first several miles are quite beautiful as the trail is often at or near the top of ridges. Open views are constant.

About two hours in, the trail intersects FS Road 2054. A trailhead is located here. Cross the road to continue your hike.

A bit less than 2 additional hours of hiking will bring you to another intersection. FS Road 300 terminates here. From this point on, the Thirteen Mile Trail heads down into more heavily forested terrain and the views aren't nearly as frequent. This is a good turnaround point.

However, I continued on, wanting to reach the highpoint of Thirteen Mile Trail where I would leave to scramble off-trail to the summit of Seventeen Mile Mountain. The trail does a lot of meandering and switchbacking and it's quite a long slog to reach that point. However, I succeeded and made it to the summit a little over 7 hours after I started the hike.

I was able to make it back to the trailhead before dark. As before, the lower section of trail, between the intersection with FS Road 300 and Highway 21 is most beautiful, especially with the long shadows of late afternoon.

I hiked the 160–170 mile section of the Pacific Northwest Trail from the Kettle River to Oroville (parts of PNT Sections 4 and 5 as described on the pnt.org site).

Some notes from the hike:

• The ancient “road” on the western side of Marble Mountain is more of a road ghost: a road-width grade cut into the mountainside, covered with trees, bushes, and blowdowns.
• The mile or so of valley between Marble Mountain and Dry Mountain (some 2–3 miles north of Boulder Creek Road) is perhaps the worst section of trail I’ve ever hiked. Although the region is generally dry, there’s water in the valley that frequently runs along the trail, turning into a marshy bog. There are not only countless blowdowns, but many still retain brushy branches, making it extremely challenging to find a way past them. I had to remove my pack at one point to squeeze through branches.
• The National Forest Deer Creek Summit Campground appears to be open. It seems to have been posted as closed in previous years, but I could find no “Closed” signage anywhere, and privies on either side of the road are open. Two other groups were camping there the night I was there.
• The Kettle Crest Trail is in great shape: easy to follow tread, very few blowdowns.
• On Edds Mountain, I took the furthest/westernmost bushwhack option. This wasn’t terrible, but not particularly fun. While bushwhacking may be part of the PNT’s current allure, I’m one hiker who would much prefer the choice of a maintained trail corridor for the complete length.
• The first half of the Thirteenmile Trail was okay, not great. I found it boring: mostly waterless, with little variety, and with hardly a view or pleasant spot where one could camp. I felt like I was walking past the same 3 trees for hours.
• The second half of the Thirteenmile Trail — after it comes out onto high meadows and heads down toward the canyon — are glorious.
• I found the Thirteenmile Trailhead described in at least one place online as a campground, but it’s little more than a gravel parking area and a privy. It was nice to rinse off in freezing Thirteenmile Creek.
• The 3 miles of early morning road walk along the Sanpoil River canyon were some of the nicest of the trip. You can still enjoy nature even when your feet are on pavement.
• The Swan Lake Campground is beautiful. I’m so glad I spent a relaxing afternoon there before spending all of the following day walking north on endless forest service roads.
• I camped at the Sweat Creek “Day Use Picnic Area”. Rather than camp near the privy, I found a more secluded spot by the creek. There’s a big boulder next to the privy: take the trail to its left. The trail bends left and goes through a wooden gate to reach the creek. There are campable spots there. That’s also where the PNT begins its ascent of Clackamas Mountain.
• On the north side of Clackamas Mountain, the old road briefly leaves the Okanogan National Forest to cross private land before reentering public lands. The PNT recommends following “flagging” to avoid that private property. I found no flagging near the road, so I ended up bushwhacking roughly along the line of barbed wire fence. I eventually did pass a couple of bits of weathered vinyl flagging tape, but this was not a well-marked detour. It was also a little challenging to cross Cougar Creek and get back on the public road.
• On Mount Bonaparte, I highly recommend taking the PNT alternate and making the short trip from the alternate to the fire lookout at the summit. There are great views in all directions.
• I’d looked forward to staying at the nice church in Havillah that hosts PNT hikers, but they’ve posted online that they’re not hosting hikers due to the pandemic. Instead, I camped at the very edge of Okanogan National Forest. A faint Road 3230 leads east from the PNT back into the forest, where it’s possible to find flattish spots for camping. Mill Creek offers water as well.
• This Whistler Canyon Trail down the west side of Mount Hull near Oroville is a hidden gem. My campsite on the bluffs overlooking the Okanogan River had a magical view, especially at night when the lights scattered across the farms below mirrored the lights of the stars above.
• With the exception of 20 minutes of rain on the first day, I had clear weather the entire time.
• I encountered very few bugs. There were some at the summit of Copper Butte, and again on the Whistler Canyon Trail, but nothing terrible.
• I heard from some hikers that the snow melted out along the Kettle Crest only in early July. That late melt may account for the spectacular wildflowers I saw all along the hike.
• I saw a fair amount of wildlife on this hike: countless deer, bighorn sheep, an elk, a fox, and a bobcat. And cows! So many cows. (To the cows in the stampede which my appearance in Okanogan National Forest triggered: my sincerest apologies.) In the evenings, I heard coyotes near Snow Peak, and loons at Swan Lake and Bonaparte Lake.

Hiked about 4 miles in on Saturday. Overall, the trail was in good shape, though there were a couple of navigable washouts (where trees next to the trail had been blown over) as well as a few good sized Ponderosa and Doug Fir across the trail. Though the lower canyon is known for rattlesnakes, we did not see or hear any.

I got dropped off on top of Sherman Pass on Friday around noon and proceeded south on the Kettle Crest South trail (#13).  There was intermittent snow that had recently fallen, but nothing too bad.  Trail is in great condition and no issues.  I reached the Snow Peak cabin and everything looked in order and there was water available at the trough nearby.  Continued south to the junction with the Barnaby Buttes trail (#7).  Note this is the Barnaby Buttes trail heading to the west, and not the other one (#70) that heads east.  The junction is marked well and the trail was in reasonable condition and is mostly an old roadbed.  Some trees down and thick grass at times, but really easy to follow and plenty of water along the way.  I made camp down near the area where the map shows this trail turning into a road, but really this continues to be a trail that is an old closed road until it reaches the Hall Creek Road (FS Rd 600).  Continued the next morning with a short road walk along Hall Creek Road to reach the junction with the Thirteen Mile trail (#23).  This is my favorite trail on the Colville NF and is really a great hike at this time of the year.  The trail was in excellent condition with just one or two trees down for the entire 16 miles.  There was water in the creek just west of the Bearpot trail junction, also in the creek at the FS Rd 2054 crossing (Cougar trailhead), and finally just a few miles before the end of the trail at the junction with highway 21.  Plenty of great places to camp along the way on some of the open balds, with old ponderosa pine, Douglas-fir, and larch throughout.  Beautiful!  All in all I think it was about 28 miles or so and represents one of the best one-way short backpack trips in the area.  Perfect in late spring or early fall.