Overview
Trinity Mountain rises above the Trinity Lakes basin in the northern Boise National Forest, one of the most scenic areas in this section of the forest. The 5.5-mile round-trip is a solid half-day hike that rewards the effort with views of the lake cluster below and the mountain terrain extending in all directions.
The Trinity area is less visited than the Grandjean gateway to the east, which makes it an appealing choice for hikers seeking a shorter, quieter route. The trailhead is accessible by dirt road and the lack of facilities keeps casual visitor traffic low. Hikers here tend to be purposeful rather than passing through.
From the summit (approximately 7,800 feet), the Trinity Lakes are visible below in the basin, reflecting the sky on calm mornings. The Sawtooth Range appears to the northeast on clear days. The surrounding Boise Mountain terrain rolls in every direction, dotted with the dark green of spruce-fir forest and the paler tones of rocky summits.
The route can be extended by continuing along the ridgeline north from the summit, which opens additional views and provides access to cross-country terrain for experienced hikers comfortable with unmarked routes.
The Route
Miles 0 to 2.0: Forest Approach
The trail begins at approximately 6,600 feet and climbs through lodgepole pine forest on a consistent gradient. The lower section is shaded and the footing good, with the trail well-maintained and easy to follow. A seasonal creek at roughly mile 0.5 provides water early in the season.
By mile 2, the forest begins to open and the gradient increases. Whitebark pine replaces the lodgepole, indicating the transition to subalpine terrain.
Miles 2.0 to 2.75: Summit Approach
The final section climbs more steeply through open subalpine terrain. Cairns mark the route above the last trees. The summit is broad enough to explore and the views expand with each step in the final approach.
When to Visit
June through October. Lower sections are accessible from late May. The summit clears of snow by mid-June in most years.
What to Bring
Many hikers carry:
- 2 liters of water; the creek source dries by midsummer, so carry sufficient water from the trailhead
- Wind layers for the exposed summit
- Sun protection
- Trekking poles for the steep upper section
Individual needs vary.
Practical Details
No permit required as of 2026. No trailhead facilities. Cell service absent. Dispersed camping permitted. Dogs allowed on leash.
Leave No Trace principles apply throughout.
Getting There
From Boise, drive north on Highway 21 approximately 75 miles to the Trinity Mountain Road turnoff. Follow the dirt road approximately 6 miles to the trailhead. Allow approximately 2 hours from Boise. Check current road conditions with the Garden Valley Ranger District before visiting.