Distance (round-trip)

13.5 mi


10 hrs

Elevation Gain

7247 ft




Iron Mountain #1, also known as “Big Iron”, is often considered one of the most remote and strenuous day hikes in the San Gabriels. This exposed and relentless, extremely rough use-trail climbs 6,000 feet to reach the summit. Once at the top, you will feel you are at the center of the San Gabriels with breathtaking views in all directions.

Red tape and warnings:

  1. Self-issued day permit required which can be found at the trailhead
  2. Adventure Pass required for parking
  3. Bring trekking poles for the steep sections
  4. Bring LOTS of water. Even if you are doing this trail in the cooler months, bring a good amount of water as there is none on the trail. I had 4-5 liters of fluids and it barely got me through the trip.

When you park at the lot, display your Adventure Pass and then walk past the gate half a mile down the road to the trailhead. This parking lot is often crowded as the trail to the popular Bridge to Nowhere hike is also down this road, so try to get here early — especially on weekends.

The road will lead you to a bathroom on your right and behind that bathroom is the trailhead. However, before going to the trailhead, first walk toward the signs several feet down the road. This is where you will pick up your self-issued day permit. The permits are located in the brown box. Fill out the form and deposit it in the box, be sure to keep a copy with you.

Now that you have your permit, walk to the trailhead behind the bathroom area. The Heaton Flats Trail is where your journey to Iron Mountain begins.

You will climb gentle switchbacks along the hillside for about 1.2 miles to reach a saddle. Along the way, you may have to cross the stream at several spots. The water level will of course depend on the time of year. When I hiked this in late November, the stream bed was completely dry, but if we’re in the wet season you can expect a bit more water up here.

Shady section of trail along the stream. Enjoy the shade while you can.

Dry stream crossing

Once you have reached the saddle, look back for some great views before you venture into the Sheep Mountain Wilderness.

At the saddle, you will see the trail climb left up the hill. Follow the trail but be sure to apply some sunscreen first. There is little to no shade in this upcoming section.

Trail leaving left from the saddle


The only sign on the entire trail

The trail begins to slowly climb up the ridge and then veers off to the left traveling along hillside.

Roughly 2.5 miles from the trailhead sign, you will reach a plateau. As you look to the northeast, you will recognize Mt. Baldy in the distance. In the foreground, there is a ridge line with several bumps. This is the ridge you must traverse to approach Iron Mountain.

Beginning of the ridge with Mt. Baldy in the background

The initial bumps along the ridge are not too strenuous; however, they become more difficult the farther you travel. Iron Mountain is the large prominence at the end of the ridge line.

Iron Mountain at the end of the ridge

As the elevation increases, the size of the yucca plants also increases. Most of them have been cut down to where they won’t stab you; however, they still hurt when you run into them. Wear long pants on this trail!

The ridge bumps become steeper as you make your way toward Iron Mountain. These relatively small inclines will give you a taste of what is to come when you reach the slopes of Big Iron — and perhaps help you understand why it got that nickname.

As you summit the last bump, you will see that the trail actually winds downhill toward Coldwater Saddle. This is rather disheartening. After losing a couple hundred feet in elevation, you’ve reached the saddle before Big Iron.

Trail leading downhill to Coldwater Saddle

From the saddle, you’ll realize just how far you have left to climb. If you work out the numbers, you actually have a little under 3,500 feet to climb in about 2.5 miles. This part of the trail makes me think of one of my favorite childhood book series, Lemony Snicket’s A Series of Unfortunate Events. Mr. Snicket often prefaced his books saying that there are many happier alternatives than reading his unfortunate tale. As Mr. Snicket gave warning to his readers, I feel I should do the same for this trail. Your physical and mental well being may be in a much better state if you were to turn around at this point. Go enjoy a tasty lunch, give yourself a pat on the back, and be satisfied with a decent 9 mile hike. However, if you choose to continue hiking this trail, know that only mental anguish and total fatigue lie in your future.

You’ve been warned.

Looking up at Iron Mountain from Coldwater Saddle

Immediately, the trail begins a quick ascent from the saddle. Beware loose rock and eroded soil that may result in multiple slips and falls as you climb.

The trail does level off in some sections which gives some respite from the relentless climb. These sections are few and far between, though. At just over 8000 feet, Iron Mountain’s summit is not nearly as tall as some its neighbors, but the elevation gain required to scale this peak is much greater than other trails nearby. For instance, nearby Mount Baden-Powell has an elevation gain of about 2,818 feet from Vincent Gap. That trail is about 4 miles to the summit. In contrast, Iron Mountain will climb nearly 3,500 feet in just 2.5 miles! Keep in mind the fully accumulated elevation gain of the entire trail is over 7,000 feet.

The landscape begins to change here too. Tall, shady pine trees replace the aggressively sharp desert plants from below.

Finally, after several false summits and a daunting amount of uphill travel, you reach a hillside covered in rock. You are nearly there.

An old survey post labeled “W15″will alert you that you have arrived. Enjoy the 360 degree views of the San Gabriels and sign the register.

Although getting to the summit was difficult enough, the 2 mile descent is strenuous in a different way. Trekking poles are useful in this section to help avoid further slips and falls. Your knees will appreciate you if you use the poles as well. Despite trying to descend slowly and carefully, I slipped about 3 times on the way down, earning myself some battle scars on my elbows and hands. Take your time and safe journeys on your way back down!

Trail guide writer for Modern Hiker. Favorite hiking regions include the San Gorgonio Wilderness, Eastern Sierras, Channel Islands and San Gabriel Mountains


Views / Vista

Trail Map


Randy Nov 12, 2019 21:11In reply to: Casey Schreiner

I cannot verify the actual miles on this hike. But I know the mileage I got on C2C , Mt Whitney,Santiago Peak San Gorgonio etc etc etc. was within a mile or so from the posted distance on your sight and All Trails, Hiking Guy. Except on this hike.

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Casey Schreiner Nov 12, 2019 08:11In reply to: Randy

GPS receiver mileage in the field is notoriously inflated -- receivers often have their numbers bumped up from satellite bounces and realignments. My GPS device almost always gives me a larger number when I'm on the trail than the number I see once I export the .gpx file and process it through software. And that's even more pronounced on a route that's predominantly on unmaintained / unestablished trails, as different people may take different routes to get along those ridgelines. The takeaway here? This route is REALLY tough - so budget more time and effort than you need :) Congrats on summiting this!

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Randy Nov 9, 2019 06:11

Did this hike last Saturday. Harder hike than I anticipated as others said it was harder than Mt. Whitney. I found that to be true. The mileage i got was a little over 20 miles parking lot to parking lot. A day later a guy posted on another site he logged 19.0 on his apple watch for this trail. I did this hike because I thought no way it could be that difficult because of the short milage. The other website has already updated their mileage which was less than modern Hiker has. Beware of this when hiking this trail as I planned my water according to the shorter miles and ran out. Trekking poles down was a must on the rocky scree steepness of the decent.

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Carl Fielden Oct 11, 2018 18:10

Hiked Iron Mountain #1 last Sunday. The hike was as strenuous as reported, but definitely a confidence booster. If you try this one, bring lots of water. I consumed six liters during this all-day hike.

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Casey Schreiner Jul 17, 2018 08:07In reply to: Mike

Glad you made it out all right! Iron Mountain #1 is a VERY SERIOUS ADVENTURE. That's why we rated it our highest difficulty and why Kristin recommends basically a full day (and in the cooler months) to do it.

Generally during the summer, we recommend leaving the foothill / lower elevation hikes for mornings and evenings. If you're in the mood for longer treks, head to the higher elevation San Gabriels - that's what I do! :)

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Mike Jul 16, 2018 20:07

Two friends and I just attempted this hike. It is absolutely no joke and is legitimately dangerous. Two of us in the group are pretty experienced/fit and both of us suffered from heat exhaustion. My legs seized up on the strenuous last 2.5 miles (with 1 mile to summit) and, given the steep nature of this stretch, I nearly fell. If you can help it, try this hike in the cooler months. We all brought more water than usual and ran out a few hours before finishing. I highly suggest to bring, at minimum, 6 liters. Turn around if you don't feel in peak condition once getting to the bottom before the last 2.5 miles. Coming down is legitimately harder than going up as the loose rocks make it extremely easy to slip. Also, yucca plants plague this, at times, overgrown trail. Definitely wear long pants and long sleeves (if it's not too hot). Finally, no one was on this trail the entire way. I would suggest a satellite phone, some way of contacting the outside world while on the trail. This is the most strenuous hike I've probably ever done. Take it seriously as it will test your physical condition as well as your mental fortitude.

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Geoffrey L Hegedus Jun 3, 2018 14:06

Looking forward to attempting Big Iron! Great write-up, thanks!

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Kristin Frendewey Apr 29, 2018 19:04In reply to: edwin.gonzalez

Nice work on completing this hike Edwin! The loose dirt and yucca are definitely the major obstacles. Trekking poles are a necessity!

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edwin.gonzalez Apr 29, 2018 11:04

Just did this one yesterday.

My biggest concern before I started was that I would have to bush whack at some point but the trail is pretty well worn the whole way. That being said, you should accept that you will get stabbed by yucca at some points or another.

Now onto the trail. This hike is the tale of two parts, before the Coldwater Saddle and after the Coldwater Saddle. Before the saddle, it's a somewhat tough hike. Not easy and you'll work up a sweat but nothing out of the ordinary. Took me about 2 hours to get to this point.

Past the saddle, you immediately start pulling your way up a bunch of loose dirt so you really need trekking poles. I saw a man with microspikes and he was having a hard time too. Things kind of get better and then they don't. The trail past the saddle is just a long slough to the top. I really can't explain to you how miserable it gets after a while. All I can say is that you have to mentally commit to a very long day on this trail and embrace the pain and misery you're going to endure. Accept that you will be taking a few steps and short breathers the rest of the way. After another 2.5 hours up, I finally reached the summit. Bring sandals to give your feet some rest and an extra pair of socks to change into for the way back. After a half hour of rest and food, it was time to head back.

Now everything that you go up, you have to come back down. The way back to Coldwater Saddle is just as brutal as the way up. All the steepness and lose dirt come back to wreck your nerves and knees. I cannot stress how much more important trekking poles are on the way back. Throw in plenty of yucca spikes and you have a very dangerous situation. It is so bad that you actually look forward to the parts where you have to climb up.

Eventually you make your way down to Coldwater Saddle and realize you still have that much more to go. It's not easy but you have nowhere else to go so you just keep pushing through the exhaustion and the burning on your feet. Eventually you will get to the trail head and question yourself whether or not you really just hiked this monster. I carried about 6.5 liters of water with me and still had some left over by the time I finished. I never felt super thirsty but I knew I was definitely not well hydrated after my visit to the restroom. The accomplishment was worth the misery.

Any hiker in SoCal, worth their salt, must try themselves on this one. Best of luck.

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