Marble Mountain in St. Joe National Forest rises above the St. Joe River drainage as one of the more prominent summits in the Idaho Panhandle portion of the forest. The 5.5-mile round trip gains 1,800 feet on a strenuous trail that delivers a rocky summit with panoramic views across the forested landscape of northern Idaho.
The summit is characterized by the marble rock formations that give the mountain its name. The pale rock contrasts with the dark conifer forests on the lower slopes, and the summit ridge provides multiple viewpoints across the St. Joe watershed.
The Route
The trail begins near St. Maries and climbs through mixed conifer forest before steepening in the upper half where the trail transitions to rocky terrain. The summit is reached at 2.75 miles with views in multiple directions. The St. Joe River drainage is visible to the north; the Bitterroot Range rises to the south and east.
Rocky sections on the upper trail require some route-finding. The marble rock surfaces can be slippery when wet; dry conditions are preferred.
What to Expect
July and August are the most reliable months for this trail. The upper sections can retain snow into July in heavy snow years. Afternoon thunderstorms are possible in August; start early.
No water is available on the upper trail; carry a full supply from the trailhead. The trail receives moderate visitor traffic by St. Joe standards; solitude is available even on summer weekends.
Nearby
St. Maries, Idaho, is about 15 miles northwest and serves as the practical hub for St. Joe National Forest hiking, with lodging, dining, and supplies. The St. Joe River and its tributary drainages provide extensive additional hiking opportunities accessible from St. Maries.
Leave No Trace
This trail receives enough use that following Leave No Trace principles is important for preserving the experience for future visitors. Stay on the marked trail to prevent erosion. Pack out all waste. Avoid camping within 200 feet of water sources or the trail. Use existing fire rings only where campfires are permitted, and check current fire restrictions at checking conditions before you go before any visit. The trail and surrounding terrain remain in good condition because previous visitors have respected these norms.
Safety Considerations
The strenuous rating reflects the trail's general character under typical conditions. Weather, seasonal snow, and trail conditions can change the experience significantly. Carry the 10 Essentials on any full-day outing. Inform someone of your plans and expected return time before heading out, particularly on longer or more remote trails. Cell service varies throughout St. Joe National Forest and may be unreliable in canyon bottoms or remote terrain.