Landslide Lake
Landslide Lake is one of many destinations from the Cline River parking area, and one of the closest. This hike is not in a park, so don't rely on signage or any sort of support. That being said, it is popular and the people you run into will likely be friendly.
The parking lot is on the west side of the highway south of the Cline River, and it is quite large.
The trail from the parking lot is well-defined and you will likely run into other people as this is pretty popular. It is easy to follow. So easy to follow that it is easy to miss the turnoff up to Landslide Lake. The turnoff is right in a very large area of campsites next to the Cline River. The trail branches off to the south and is is much narrower with fewer people traveling this way. There are parts of this trail that often get washed out every year or two so route-finding here might be tricky. Map and compass are highly recommended. If the trail has not been washed out for a year or two, it should be easy to follow. It climbs up through the forest until you reach the lake. At the lake, the trees are a little more patchy, and there are nice day-hikes from the lake that will take you up above the treeline.
This trip is most commonly done as an in-and-back trip, but some people continue past the lake, climb up the pass, and descend to the highway. For this option you will either need to arrange transportation back to your vehicle or try your luck hitchhiking.