The South Lost Lake Trail makes up the far southern portion of the Larrabee State Park trail system, located just south of the city of Bellingham. The lake itself rests on the east side of Chuckanut Ridge, and it is often hiked in combination with nearby Fragrance Lake.
The beginning of the route ambles northeast from the Clayton Beach Trailhead along Fragrance Lake Road. The grade steepens before long, following some wide switchbacks through mixed forests and fern-filled gullies. At 1.3 miles, a roadside waterfall pours down to a culvert underfoot. Less than a mile further lies the signed junction for the official Lost Lake Trail as well as “back-door” access to Fragrance Lake.
The narrower Lost Lake footpath jets off on a long southeast traverse beneath Chuckanut Ridge. Notice the lighting change as deciduous forests of red alder and bigleaf maple begin to replace the heftier cedar and fir. Stick close to the trail along this stretch, for hordes of stinging nettle line the edges during the spring and summer months. At 4 miles from the parking lot, another junction comes along for the utterly impressive Rock Trail. Here, the south end of Lost Lake lies obscured only a few hundred feet below. Continue a mild descent above the east shore to a junction for the North Lost Lake Trail. Head right to travel around the west lakeshore, where you’ll find the highlights of the trip: a gushing waterfall and giant rock with sweeping views of the lake.