Backpack Trail Guide

Trails / Idaho / Sawtooth Mountains

Marten and Kelly Lakes via Trap Creek

Sawtooth National Recreation Area (Trap Creek, west of Stanley off Idaho Highway 21)

Marten and Kelly Lakes make an easy overnight on the quieter west edge of the Sawtooth National Recreation Area. Hiking Boise says you won’t find many other Sawtooth trails with such a gentle climb and lakes along the way. The first stretch passes through a burn, then the trail follows Trap Creek up into forest to a pair of lakes below a ridge.

One Idaho trip list says the route can be done in a day but that backpackers recommend it as a quick overnight.

The hike

The trip starts at the Trap Creek Trailhead, off Idaho Highway 21 west of Stanley. Trailforks says the access road is poorly signed and easy to miss in the trees, and that you can park by the highway or drive about 0.8 mile up a rough, narrow road to the trailhead. One hiker who measured it put the trailhead at 6,695 feet. Hiking Boise gives a starting elevation of 6,873 feet.

The trailhead and first mile burned intensely in September 2020, according to Hiking Boise, and the area has seen little regrowth. Outbound describes the first half of the hike to Marten as mostly flat and barren, with charred trees. One AllTrails reviewer called it burned the whole way with very restricted views, and another said the burned section was under a mile. The Forest Service’s 2024 trail report listed the Trap Creek Trail as closed because of the Wapiti Fire. Its July 2026 report shows the trail maintained that year with no closure listed. The Forest Service describes the Trap Creek Trail (#627) as a 3.5-mile motorized single-track trail, so watch for motorbikes.

After about half a mile heading south, Hiking Boise says, the trail turns southwest at a meadow bisected by Trap Creek and follows the creek’s drainage toward Marten Lake. Outbound suggests stopping to rest and refill water once you hear the creek, after which the forest fills in and the trail starts to climb. One hiker found the climb very easy, with only gentle hills; the hardest part comes near the end and lasts about 0.4 mile.

At about four miles, you reach a junction with the Swamp Creek Trail, which Hiking Boise says is open to dirt bikes. Go straight and down a short spur to reach the grassy outlet of Marten Lake. Hiking Boise says it’s framed by the ridge that forms the boundary between Boise and Custer counties, and Outbound and another guide put it at about 7,615 feet.

To reach Kelly Lake, return to the junction and turn south on the Swamp Creek Trail. Hiking Boise calls it less than a mile and about 350 feet of climbing, and describes Kelly as the more scenic and larger of the two lakes. Outbound puts Kelly at about 7,900 feet. A third lake, Elizabeth, is also on the route network. Outbound lists it as another camping option, and a Gaia GPS route from Bench Creek passes Elizabeth and Kelly on the way to Marten.

Round-trip figures run from about 8 miles to Marten alone up to about 10 miles with the side trip to Kelly. Hiking Boise gives about 1,240 feet of gain and a season of June to October.

For comparison, Sawtooth Lake via Iron Creek is also reached from Highway 21 near Stanley. Outbound says most weekend backpackers stick to Sawtooth Lake, while trails like this one see considerably less foot traffic.

Tips

Camping

Camping is dispersed. Hiking Boise says there are great campsites at both lakes if you’re backpacking. We could not find a permit requirement for this route; because the trails are open to motorbikes, it doesn’t appear to be inside the Sawtooth Wilderness, but confirm with the Stanley Ranger Station. Because this route is outside the wilderness, the Forest Service’s food storage order for the Sawtooth National Recreation Area applies from the Saturday before Memorial Day through Labor Day. The Forest Service says food and other attractants must be kept in a bear-resistant container, a hard-sided vehicle or building, or hung at least 10 feet off the ground and 4 feet out from a tree or pole. Check fire restrictions before you go.

Inside Intel: Kelly is the lake to aim for if you have the energy. Hiking Boise calls it the more scenic and larger of the two, and it’s under a mile past Marten. One AllTrails reviewer found Marten itself not that inspiring. If you do camp at Marten, one hiker found a campsite on the north side of the lake, about 0.4 mile past the junction. Outbound’s suggestion is to try all three lakes, Marten, Kelly, and Elizabeth, and pick the one you like.

Trail facts

The Lowdown

A gentle first overnight:

An easy climb to two lakes makes this a good trip to break in a new tent. See which tents held up for testers.

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Where this comes from

This page draws on the sources below, along with other guides and trip reports. Links go to the original pages.

Before you go: This page is based on published trail guides, trip reports, and reviews, along with official park and agency information where we could find it. It’s meant to help backpackers discover new trails, not to replace current, official information. Conditions, closures, permits, campsites, and water sources change, and some details here may be out of date or wrong. Confirm everything with the managing agency and check current conditions before you head out, and don’t rely on this page alone for safety or navigation. Backcountry travel involves risk.