Varied Terrain and Numerous Lakes
I've set this hike to begin at Summit Lake North Campground because that was my starting point. There is public parking available at the true trailhead at the Summit Lake Patrol Cabin about 1/3 mile west on the Echo Lakes Twin Lakes trail.
My starting point was a small, signed trailhead at the eastern end of Summit Lake North Campground. There's also a sign for the amphitheater between the northern and southern campgrounds. The spur trail from the campground joins the official trail after traveling about 100 yards and over wooden decks over the marshy area where Dersch Meadows meets Summit Lake. There is another junction about 100 yards ahead at the junction of the trail to the amphitheater and Echo Lakes Twin Lakes trail. There was a map here showing which parts of the trail were damaged by the 28,000-acre Reading Fire in 2012. Just think of this loop as a clock, and the burned area is bewteen 8 o'clock and 2 o'clock.
The trail goes a little less than a mile to yet another junction. Go right to see Echo Lake, or go left on the Bear Lakes Trail to travel through the burned area where the trail is mostly downhill. I decided to go clockwise because I typically prefer to go uphill in the shade. The hike to this point has been uphill at a pretty respectable grade, and it gets steeper until you finally top out around 1.5 miles and 500' higher than the trailhead. The typical vegetation here is red fir and lodgepole pine scattered amongst pinemat manzanita. The relatively sparse tree cover typically means hiking in the sun, but there are views of Lassen Peak behind you to compensate.
The Bear Lakes trail is somewhat flat with a slight downhill grade until the first lake appears about 2 miles in on the left. The lake isn't much, and it's surrounded by the post-fire mosaic of black toothpicks and health trees. About 3 miles in there is a somewhat steep section heading down to Little Bear Lake that offers great views of Prospect Peak (8,338'), West Prospect Peak (8,174') and Badger Mountain (7,127'), particularly if you go off-trail a bit to the right.
The junction with the Cluster Lakes Trail and its namesake lakes is about 4.5 miles in. Cluster Lakes travels 2.7 miles north to the Pacific Crest/Nobles Emigrant trails. The forest here is decidedly more burned than not here, but most of the trees around lakes seem to have made it. Going a few hundred yards north on Cluster Lakes features a number of great views of 2 unnamed lakes before heading into a severely burned area. Continue on the Bear Lakes Trail as it passes Silver and Feather lakes on the right. The Pacific Crest Trail junction is about 7.5 miles, and the dense tree cover has returned. That's the good news. The bad news is that so have the bugs, particularly mosquitoes. These lakes have a few nice camping spots, but the lakes are too shallow for swimming. Back country permits are required for camping.
Stay on the Pacific Crest Trail for about 3/4 mile as it heads around the east shore of Lower Twin Lake. The Echo Lake Twin Lakes Trail has a junction with the Pacific Crest Trail at the northern end of Lower Twin Lake at right about 3 o'clock, but I chose the eastern shore. Lower Twin and Upper Twin lakes are the most magnificent lakes on this hike, and you're likely to see a number of people. There are numerous campsites around these lakes, and is somewhat popular for short backpack trips.
The hike has been downhill since the initial high point in the burned area, but now it's time to gain back most of that elevation. Continue on Echo Lakes Twin Lakes Trail as it passes a slender unnamed lake before reaching Echo Lake. Echo Lake is popular for short dayhikes from Summit Lake. There are a couple of short lung and quad burning stretches before getting back to the junction with Bear Lakes. It's about a mile downhill to the campground where your ice chest awaits.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.