Hike Mt Islip From Crystal Lake

10.5 miles - Hard Effort
4-5 Hours (Total)
2,800 Total Feet of Climbing
Max Elevation of 8,250 feet
Leashed Dogs Allowed

Tucked into Angeles National Forest away from the crowds, this loop hike to Mt Islip from Crystal Lake offers a little bit of everything in a very doable package. Starting at one of the only natural lakes in Angeles National Forest, Crystal Lake, the hike follows well-marked trails, offers spectacular views, and summits Mt Islip at 8,250 ft. After soaking in the sweeping views from Catalina to the Mojave, you have a long, gradual downhill cruise back to the Crystal Lake Recreation Area.

In this Guide:

Turn by Turn Hike Directions & Video
Mt Islip Trail Maps
How to Get to the Crystal Lake Trailhead
Points of Interest on the Hike

Quick Links:
Parks Pass - Park Website - Weather Forecast - My Apr 2024 Gear

How to Get To the Crystal Lake Trailhead

The hike starts at the Crystal Lake Recreation Area at the end of Rt 39. The drive up Rt. 39 is a fun one as it winds up through the mountains. Rt 39 used to connect with the Angeles Crest Highway just after the trailhead area, but the highway closed after a mudslide in 1978. The trailhead for the hike is just before the campground area at the actual (Crystal) lake.

Use this trailhead address:
Crystal Lake Recreation and Picnic Area, N Crystal Lake Rd, Azusa, CA 91702

Rt 39 can close during snow and ice, so check the CalTrans website before you go.

Crystal Lake Closeup — The trailhead is just on a turnoff to the left as you enter the recreation area.. It can get a little confusing because there's a lot going on. From the trailhead parking you continue clockwise on the loop to reach the visitor center and general store.

Mt Islip Hike From Crystal Lake 1 — Shortly after seeing the sign for the Crystal Lake Recreation Area you'll make the left turn on the loop road to find the trailhead parking.

Crystal Lake Trailhead Parking — There's a decent amount of parking at the trailhead.

Mt Islip Hike From Crystal Lake 4 — There are primitive toilets at the trailhead too.

Crystal Lake Recreation Area has dozens of campsites, some with RV hookups; if you want to stay the night, you certainly have a good option here. I never see it full, but on summer weekends it does attract visitors. Campgrounds are first-come,. first-serve, and not bookable on the Recreation.gov website.

There's also a small visitor's center manned by volunteers and general store, the Crystal Lake Cafe, which has food and camping basics like firewood. There's no beer or alcohol at the store, so bring it up yourself.

Mt Islip Hike From Crystal Lake 60 — The visitor center is manned by volunteers and has limited hours. If you don't have a National Parks Pass you can buy an Adventure Pass here.

Mt Islip Hike From Crystal Lake 61 — The general store offers local delicacies.

There's also an amphitheater here that is allegedly haunted.

Gear For the Hike

You'll definitely want full-on hiking gear on this hike. Bugs can be bad in the summer, and in the winter it's smart to throw micro-spikes in your pack. Trekking poles will help on the climb and descent.

If you want to check if there's snow on your hike, read this guide.

Gear That I Love Right Now

Nothing is sponsored or promoted, just the actual gear that I use.

Garmin InReach Mini 2If you are out of cellphone range the Mini 2 will reliably allow you to hit SOS via satellite. You can see my review here.

HOKA Speedgoat 5These are a great balance of comfort and performance. The high stack height leaves my feet feeling great after a hike.

Check out the complete list here.

Mt Islip From Crystal Lake Trail Maps

While these aren't the most popular hiking trails in Angeles National Forest, they are very well marked. Signs get stolen though, so be prepared. And if you're using OSM maps, note that some trails are incorrect. The GPX file that I have here is correct based on the trails and directions that you find in this guide.

Use This Map:
View in CalTopo | PDF Map | GPX File

How Will You Navigate?

Using the Apple Watch for Hiking

Garmin Fenix 7 & Epix Review For Hikers

How To Read a Topographic Map

Garmin GPSMAP 67i Review

Elevation Profiles

Mt Islip From Crystal Lake Hike Elevation — Aside from some minor bumps, it's a pretty straightforward up and down on this hike.

Mt Islip From Crystal Lake Hike 3d Map — You do a bit of a loop on the mountains surrounding the Crystal Lake area. From the lake, it's up the ridge to Mt Islip, then back down to Windy Gap and the valley.

Hike Landmarks

Landmark	Distance	Elevation
Crystal Lake Trailhead	0	5200
Exit the Lake Shore	0.5	5200
Start of Ridge	1.6	6100
Big Cienga Junction	4.2	7600
Mt Islip Summit	5.5	8250
Windy Gap	6.5	7588
Deer Flat Campground	8.6	6600
Lost Ridge Trail	8.8	6400
Trailhead	10.5	5200

Hike Brief

Crystal Lake Postcard — The campground at Crystal Lake has been around since 1932. The closeness to LA made it popular with those escaping the city, and according to a local Crystal Lake was “one of the most popular places in Southern California . . . a regular Coney Island." The campground area includes a general store, visitor's center, and amphitheater.

Crystal Lake is one of the only naturally formed lakes in southern California. Most "lakes" that you see in SoCal are man-made or are actually sag ponds, which is where a fault opened up and ground water seeped in. As a true lake, Crystal Lake fed only by snow and springs. Depending on when you visit, the water level can be low or high; Crystal Lake tends to go way down when we're in a drought. When the lake is full it's 130 feet deep. Note that there is no swimming in the lake today, and the waters aren't as crystal clear as they used to be.
The area was originally settled by gringos in the mid-1800s when hunters were attracted to the lake because it was a popular watering hole for grizzly bears and other animals. The grizzlies are long gone but the remoteness of the area often attracts big horn sheep; keep your eyes open for them on the slopes. The lake is also used to be stocked with rainbow trout but hasn't been in some years.
The 2002 Curve Fire did a number on this whole area, including the campground and all the way to the summit of Mt Islip. You'll see evidence of the fires on the hike. The damage was pretty bad and the area didn't reopen until spring of 2011.
Mt Islip (pronounced eye-slip) is named after George Islip, an Englishman who settled here in the 1880s.
A fire tower once stood on Mt Islip, and you can see the old foundation and stone living quarters when you get to the summit. The fire tower went up in 1928 but only stood on Mt Islip for 10 years; in 1938 it was moved to nearby South Mt Hawkins where it stood until it burned down in the 2002 Curve Fire. Mt Islip was also home to one of the first two-way radios used by the Forest Service for fire reporting. There used to be several fire towers covering Angeles National Forest. They were abandoned in the 1960s and 70s when the smog became so bad that they were ineffective.

Mt Islip Fire Tower And Hut — Here's what the fire tower and stone hut looked like back in the day. Photo credit: Bob Cates

Mt Islip From Crystal Lake Hike Directions

Mt Islip Hike From Crystal Lake 3 — The trail starts past the gate at the trailhead.

Mt Islip Hike From Crystal Lake 5 — There's a short climb to wake your legs up.

Mt Islip Hike From Crystal Lake 6 — And then you'll come out above Crystal Lake, which looks more like a black lagoon. You're going to circle the lake in a counterclockwise direction.

Mt Islip Hike From Crystal Lake 7 — Keep circling the lake at the beach area, avoiding the stairs to the left.

Mt Islip Hike From Crystal Lake 8 — Lots of California Toads along the shore.

Mt Islip Hike From Crystal Lake 9 — When you're about 80% around the lake, look for a trail heading away from the water and up.

Mt Islip Hike From Crystal Lake 10 — Keep heading up and bear to the right. You're basically going to be going back along the southern shore of the lake, but up on the hill.

Mt Islip Hike From Crystal Lake 11 — When you gain the top of the hill, bear right to hike back along the lake.

Mt Islip Hike From Crystal Lake 12 — Continue up above Crystal Lake to your right and below.

Mt Islip Hike From Crystal Lake 13 — When the southern short of Crystal Lake disappears, bear left to start hiking up the climb.

Mt Islip Hike From Crystal Lake 14 — The trail climbs up offering some nice views.

This trail is known as both the Islip Ridge and Islip-Wawona trail. Different maps have different monikers for it.

Mt Islip Hike From Crystal Lake 15 — As you climb toward the ridge you'll see evidence of the 2002 Curve Fire.

Mt Islip Hike From Crystal Lake 16 — While this trail might not be too popular, it is well maintained and easy to follow.

Mt Islip Hike From Crystal Lake 17 — After a series of switchbacks you'll reach the ridge line which you'll ascend to Mt Islip.

Mt Islip Hike From Crystal Lake 18 — The ridge line has some nice flat sections mixed in with climbs.

Mt Islip Hike From Crystal Lake 19 — The trail is in good condition but there can be some downed trees and obstacles. This isn't Icehouse Canyon, the trail is lightly used and sometimes needs a little TLC.

Mt Islip Hike From Crystal Lake 20 — As the trail hits the west side of the ridge you get some incredible views.

Mt Islip Hike From Crystal Lake 21 — There are some sections that go through shrubs but again, always easy to follow.

Mt Islip Hike From Crystal Lake 22 — As you ascend you'll get some great views of Mt Waterman and Twin Peaks.

Mt Islip Hike From Crystal Lake 23 — When you gain this flat section you'll see Mt Islip in the distance.

Mt Islip Hike From Crystal Lake 24 — When you reach the Big Cienga Trail junction, bear left toward Mt Islip.

Mt Islip Hike From Crystal Lake 26 — Here's a closeup of the sign at that trail junction.

Mt Islip Hike From Crystal Lake 27 — The trail gets rockier and there are some limber pines as you approach Mt Islip.

Mt Islip Hike From Crystal Lake 28 — To reach the summit, look for the spur trail off to the left.

Mt Islip Hike From Crystal Lake 29 — Just before you reach the summit you'll see the ruins of the old watch-keeper's hut.

Mt Islip Hike From Crystal Lake 30 — Here it is, the summit! The concrete blocks are the base of the old fire tower.

Mt Islip Hike From Crystal Lake 32 — No, this isn't dog poop, it's the trail register (bag).

Mt Islip Hike From Crystal Lake 33 — The views are great, from Mt Baldy to Mt Lukens to the Mojave.

Mt Islip Hike From Crystal Lake 31 — When you're done at the summit, head back down the way you came.

Mt Islip Hike From Crystal Lake 34 — At the spur trail junction, head left.

Mt Islip Hike From Crystal Lake 35 — The descent is easy to follow, a gradual gradient, and a welcome break after all the climbing before.

Mt Islip Hike From Crystal Lake 36 — Keep your eyes open to your right for Crystal Lake in the distance.

Mt Islip Hike From Crystal Lake 37 — Make the hard right at the junction to leave the Mt Islip Trail and head toward Windy Gap.

Mt Islip Hike From Crystal Lake 38 — After a short while you'll see Windy Gap and the PCT in the distance.

Mt Islip Hike From Crystal Lake 39 — Make the hard right at Windy Gap to head down the WIndy Gap Trail. If you went straight you'd join the PCT and eventually reach Mt Baden Powell.

Mt Islip Hike From Crystal Lake 40 — Here's a closeup of the trail sign for Windy Gap Trail at the junction. We're heading back down towards Crystal Lake.

Mt Islip Hike From Crystal Lake 41 — Enjoy the nice long descent that you can really cruise down.

Mt Islip Hike From Crystal Lake 42 — Go straight at the junction of the Big Cienga Trail. You passed the other end of the trail shortly before you reached Mt Islip.

Mt Islip Hike From Crystal Lake 43 — Here's a closeup of the sign at that junction. Keep heading toward Crystal Lake.

Mt Islip Hike From Crystal Lake 44 — Shortly after that last junction there's another one. Hike to the right here.

Mt Islip Hike From Crystal Lake 45 — Here's the sign at that last junction. Deer Flat Campground is our next stop.

Mt Islip Hike From Crystal Lake 46 — The trail follows an old road.

Mt Islip Hike From Crystal Lake 47 — And ends at the Deer Flat Campground. Go through the gate, keep left and go straight on the road through the campground.

Mt Islip Hike From Crystal Lake 48 — There are primitive toilets here in case you're experiencing "a situation."

Mt Islip Hike From Crystal Lake 49 — Keep bearing left on the paved road. The campsites will be down to your right.

Mt Islip Hike From Crystal Lake 50 — When you see this intersection, make the righ to hit the Lost Ridge Trail.

Mt Islip Hike From Crystal Lake 51 — Here's the sign at that junction.

Mt Islip Hike From Crystal Lake 52 — The Lost Ridge Trail starts to the left after you make the last turn.

Mt Islip Hike From Crystal Lake 53 — Head down the Lost Ridge Trail which will take us back to the start of the hike.

Mt Islip Hike From Crystal Lake 54 — The trail is a bit overgrown but easy to follow. You'll follow the road (up to the left) for a short while.

Mt Islip Hike From Crystal Lake 55 — Being watched by a Western Fence Lizard. I don't think the animals see many humans on this trail.

Mt Islip Hike From Crystal Lake 56 — At the junction bear right toward Crystal Lake.

Mt Islip Hike From Crystal Lake 57 — The trail follows the road (down to the left) for a bit.

Mt Islip Hike From Crystal Lake 58 — Then pops you on onto the pavement. From here continue on the paved section for a short while.

Mt Islip Hike From Crystal Lake 59 — And then you'll reach the trailhead parking lot where you started. And that's the hike!

Need More Info?

Have a question about the guide or want to see what other people are saying/asking? View the Youtube comments for this video. Leave a comment and I will do my best to respond.
When planning, always check the park website and social media to make sure the trails are open. Similarly, check the weather and road conditions.

Related Guides

Hike Mt Waterman & Twin Peaks

Mt Baden-Powell Hike

Mt Hawkins Loop Hike (Hawkins, Middle, and South Mount Hawkins)

Los Angeles Hikes

Angeles National Forest Hikes

Backpacking Trips

Fire Tower Hikes

LA Mountain Hikes

Sierra Club 100 Peaks

Popular Guides

Best Hiking Gear 2024

Hiking Boots or Shoes: Do I Really Need Hiking Boots?

When to Hit SOS on inReach

This Guide Was Written by Cris Hazzard

Cris Hazzard 4 Mile Trail Yosemite
Hi, I'm Cris Hazzard, aka Hiking Guy, a professional outdoors guide, hiking expert, and author based in Southern California. I created this website to share all the great hikes I do with everyone else out there. This site is different because it gives detailed directions that even the beginning hiker can follow. I also share what hiking gear works and doesn't so you don't waste money. I don't do sponsored or promoted content; I share only the gear recommendations, hikes, and tips that I would with my family and friends. If you like the website and YouTube channel, please support these free guides (I couldn't do it without folks like you!). You can stay up to date with my new guides by following me on YouTube, Instagram, or by subscribing to my monthly newsletter.