Tunnel Light Marathon: Pacing & Race-Day Strategy
A pitch-black tunnel start under the Cascades, then a relentless downhill rail-trail to a Boston qualifier.
Last updated
No date announced yet
The 2027 date has not been announced yet. The race has historically run in mid-September.
- Where:
- North Bend, Washington
- When:
- September
- Course:
- Steep net downhill · rail-trail
- Best run as:
- Even pace
Course & elevation
Tunnel Light begins inside the former Snoqualmie railroad tunnel, where headlamps light a flat, two-mile descent through the dark before you burst into daylight on the Palouse-to-Cascades rail-trail. From there the crushed-gravel grade falls steadily for the entire race, well over a thousand feet of net drop, making it one of the most reliable BQ-chasing courses anywhere, provided your quads can take the pounding.
- Start → Finish
- 2,550 → 500 ft
- Net
- −2,050 ft
- Total gain
- ≈ 267 ft
The certified route
Point to point on the Palouse to Cascades State Park Trail: starting at Snoqualmie Pass by the Snoqualmie Tunnel, with an initial out-and-back to a turnaround, then north along the rail-trail past Lake Keechelus to the finish.
- Start
- The Palouse to Cascades State Park Trail at Snoqualmie Pass by the Hyak parking area, near the Light at the End of the Tunnel sign.
- Finish
- The Palouse to Cascades State Park Trail, 133 m from marker TP215534 per the finish detail.
Underfoot
Gravel rail-trail throughout.
Through, in order
Snoqualmie Pass · North Bend
What you pass
- The Snoqualmie Tunnel at the start
- Lake Keechelus along the southern section
- The Palouse to Cascades State Park Trail for the full course
Worth knowing
- The certificate lists a drop of 6.71 m/km and 40.86 percent separation.
- Measured using the full width of the trail and the shortest possible route.
Transcribed from the USATF certificate for Tunnel Light Marathon (WA26026RMB), measured 14 May 2026 and 6 July 2026. Where the certificate is silent, so are we.
Key moments
- Mile 0–2Headlamp-lit descent through the cool, dark Snoqualmie Tunnel. Mind your footing on the gravel.
- Mile 3–20Steady, uninterrupted downhill on the shaded rail-trail; resist the urge to hammer and let gravity do the work.
- Mile 23–26.2The grade eases near the finish, and quad fatigue bites here, so keep turnover quick and light.
Pacing strategy
Run the descent with a short, quick, low-impact stride rather than braking or over-striding. Pounding the downhill early will blow your quads by mile 18. Even effort on this grade naturally banks a fast time, so stay smooth and patient.
Pacing by goal time
Checkpoint splits for four common goals at Tunnel Light Marathon. These are effort-even rather than pace-even: the paces shift with the course profile, so climbs are slower and descents faster by the amount the grade actually costs. For any other goal time, use the planner below.
| Checkpoint | Sub-3:00 | Sub-3:30 | Sub-4:00 | Sub-4:30 |
|---|---|---|---|---|
| Mile 3.1 | 20:436:54/mi | 24:108:03/mi | 27:379:12/mi | 31:0410:21/mi |
| Mile 6.2 | 41:216:52/mi | 48:148:01/mi | 55:089:09/mi | 1:02:0110:18/mi |
| Mile 9.3 | 1:01:516:50/mi | 1:12:107:58/mi | 1:22:289:07/mi | 1:32:4710:15/mi |
| Mile 12.4 | 1:22:256:52/mi | 1:36:098:01/mi | 1:49:539:09/mi | 2:03:3710:18/mi |
| Mile 15.5 | 1:43:076:54/mi | 2:00:198:03/mi | 2:17:309:12/mi | 2:34:4110:21/mi |
| Mile 18.6 | 2:03:466:52/mi | 2:24:248:01/mi | 2:45:019:09/mi | 3:05:3910:18/mi |
| Mile 21.7 | 2:24:206:50/mi | 2:48:247:59/mi | 3:12:279:07/mi | 3:36:3110:15/mi |
| Mile 24.9 | 2:44:506:50/mi | 3:12:197:58/mi | 3:39:479:07/mi | 4:07:1610:15/mi |
| Finish | 2:58:306:50/mi | 3:28:157:58/mi | 3:58:009:07/mi | 4:27:4510:15/mi |
Splits assume even effort and are adjusted for this course's climbs and descents, which cost more than they give back. A model, not a promise: wind and heat move real splits around. See how the pacing model works.
Plan your mile splits
Turn your goal time into a mile-by-mile plan for Tunnel Light Marathon, built from this course's elevation. The even pace approach comes pre-selected, and grade-adjusted pacing evens out your effort across the climbs and descents.
Plan Tunnel Light Marathon splitsFueling & hydration
Aid stations are spaced along the rural rail-trail (roughly every 2–3 miles) with water and sports drink; carry your own gels and a flask, since the remote course offers fewer stops than a city race. The cool, easy downhill rhythm makes it tempting to skip fuel, so keep a disciplined gel schedule.
Weather
Mid-September in the Cascade foothills is crisp and often damp at the early start (40s–50s°F), with the tunnel noticeably cold. Once you’re moving, racing temperatures are ideal.
What race morning has actually been like
The last 5 editions of Tunnel Light Marathon, measured at the start line rather than averaged across the month. Starts have run 51–62°F, averaging 57°F.
| Year | Date | Start | Dew pt | Wind | By late morning |
|---|---|---|---|---|---|
| 2021 | Sep 12 | 51°F | 55°F | 3 mph | 59°F |
| 2022 | Sep 11 | 62°F | 55°F | 3 mph | 69°F |
| 2023 | Sep 10 | 59°F | 48°F | 5 mph | 74°F |
| 2024 | Sep 8 | 61°F | 61°F | 3 mph | 77°F |
| 2025 | Sep 14 | 54°F | 52°F | 2 mph | 57°F |
The gap between the gun and late morning matters here. In 2024 it went from 61°F at the start to 77°F by late morning. A four-hour finisher ran a materially different race from a three-hour one.
Dew point has reached 61°F (2024). Above about 60°F, sweat stops evaporating efficiently and most runners lose pace no matter what the thermometer says. It is the number to watch here, not the air temperature.
Dates derived from the race's published pattern (2nd Sunday in September), observations at Hyak, WA (start). Source: Open-Meteo historical reanalysis (ERA5), 7-11am local at the start line. Reanalysis is modelled from station observations, so treat it as a close record rather than an official one. See how race-morning weather is built.
Is Tunnel Light Marathon a good Boston qualifier?
It can be, but with an asterisk. The course drops 2,050 ft net, which puts it in the band where the B.A.A. adds 5:00 to your submitted time for 2027. That does not disqualify the race. It means you need to run 5 minutes faster here than the standard alone suggests.
A drop this size is fast and punishing at once. Sustained descent loads the quads eccentrically, and runners who have not trained for it tend to lose more in the last 10K than the profile gave them in the first. If you target this race, train downhill specifically.
This drop is our estimate rather than a figure from the course's certificate. If it sits near a threshold, confirm with the organizer.
Compare every course, how the downhill bands work, or work out your own target.
Dial in your pacing & fueling
New to how training builds toward a race like this? Start with Anatomy of a Running Plan, find your zones with the pace calculator, and plan race-day nutrition with the fueling calculator.
Related marathon guides
- Skagit Flats MarathonBurlington, Washington · SeptemberAlso run in September
- Eugene MarathonEugene, Oregon · Apr 25, 2027In neighboring Oregon
- Colorado MarathonFort Collins, Colorado · May 2, 2027Also carries a 5-minute downhill adjustment
- St. George MarathonSt. George, Utah · Oct 3, 2026Also carries a 5-minute downhill adjustment
Train for Tunnel Light Marathon
Build a free, personalized marathon plan that progresses you safely to race day, with paces tuned to your goal.
Create your free plan