Navigating the JMT and Emergency “Beacons”

(or GPS vs Phone vs SPOT vs InReach vs… Oh My!)

A couple friends planning to hike the John Muir Trail this summer have already asked, and it was a recurring thread on a few discussion groups last year. So I thought I’d capture my thoughts. “Which of the electronic gizmos should I bring to navigate? And what about an SOS signal?”

Executive Summary: 

  • You should bring a paper map. If you don’t need SOS/Communication capability, a map is sufficient, but your smartphone with an app (either GAIA or Guthook) and downloaded maps can be a useful aid, too. If you’re bringing your phone for before/after the hike, or photos, you might as well have the GPS handy.
  • If you want SOS/Communication capability, add the Garmin InReach to that.

The Longer Version

You definitely want a map.

First, you generally do not need either a GPS or one of the emergency satellite signaling devices. People have been hiking the JMT for decades without them. The JMT is well marked, signed, very well trodden by human and beast alike. It’s easy to follow, with prominent landmarks, peaks and lakes throughout. (Well, unless it’s covered in snow!) During peak season, it’s also busy. You’ll pass or be passed by people in both directions very frequently.

In terms of maps the three biggies are the Harrison maps, the National Geographic map, and Eric the Black’s pocket atlas. They all have subtle advantages and disadvantages, but I’d be comfortable with any one of them. (Note, if you’re going NOBO out of Horseshoe Meadows, you’ll want a supplement from there to Crabtree—none of the above provide that coverage. I used Wenk’s 2-page version: and

Evaluating all three, I slightly preferred Eric the Black atlas primarily because I found it easiest to read while walking, with sufficient detail for the JMT super highway. And it fit well in my pocket.

Personally, I think it’s important to be able to read a map, figure out where you are, and figure out where you’re going.

And a way to communicate with the outside world? I’d urge you to ask yourself, why? The more time you spend mentally off the trail, the less you get to enjoy the trail.

Also, don’t think an emergency beacon will get you out of any jam. Sometimes signals don’t get out. Sometimes conditions prevent SAR from safely coming to get you (e.g., poor visibility, high winds) First and foremost, you are responsible for your safety. Your second line of defense is your fellow hikers—and you’ll find a generous and resourceful lot out there, so don’t hesitate to ask for help when you need it.

But that’s not the question you asked!

I don’t think you need a dedicated GPS at all.

Your Phone

If you want GPS, your smartphone can fill that role as a GPS with a much better screen and interface than anything you’ve likely used before. No, you don’t need cell reception for this! Put in airplane mode, with the GPS on, and your phone will receive the GPS signal, and the battery can easily last a week (if you’re not using it much). There are a variety of inexpensive GPS apps that you can then use, downloading maps and routes ahead of time. GAIA is a good one, especially if you’d like this functionality on your phone for other hikes, too. (Nice discussion of using GAIA and CalTopo, although not JMT specific.) There is also the Guthook JMT app, not as flexible or robust as GAIA, and a bit dated looking, but it super simple with very little learning curve, download the app, and you’re done. I found it very well-dialed into the JMT, including with current user comments that can be useful if conditions are bad, and you sync right before you hit the trail. With GAIA, you’ll have to sort through and choose the right maps and waypoints. (Not that difficult, you’ve just have to learn how that works.)

In terms of communication via cell, there are only a few spots along the trail with cell service: sketchy at the top of Whitney, some around Reds Meadow, and a few points in Yosemite. If you want to be able to communicate or send an SOS message, the Garmin InReach is the way to go (see below). The JMT is busy, and you’ll see multiple groups every day, so I wouldn’t consider it a necessity.

Communicating and Sending for Help:
SPOT vs. InReach vs. ResQLink

OTOH hand, in case of a medical emergency, a faster call for help is usually better. The primary options are SPOT or InReach, or a true personal locator beacon like the ResQLink. I’ve used all three (although fortunately never deployed the ResQLink in an emergency situation).

My recommendation: If you feel the need for this, the InReach is the best choice for the JMT.

In 2017, I brought the InReach primarily because I have one already—it’s a wise choice for some of my more crazy technical canyoneering trips in more remote areas—and because I needed to be reachable because of a family medical issue. Depending on the model (I have the Explorer+), it also has an integrated, although rudimentary, GPS, clunky interface, and small screen…but more rugged than a smartphone. It’s very user friendly when you sync it with your smartphone via Garmin’s Earthmate app. In the wide open spaces of the JMT, it generally finds a satellite pretty well. Its biggest advantage over the SPOT or ResQLink is that it allows for two-way texting via satellite. This may be of interest for check-ins, where unlike the SPOT you’re not limited to preset messages. It’s very useful in an emergency because you can provide more specific information to SAR. InReach is the most expensive of these three options.  The Hiking Guy gives a good comprehensive review of the InReach.

That said, if you absolutely, positively need to get a message out, the ResQLink is the clear winner. (It’s also a one-time purchase—no ongoing usage fees.) It has a much stronger transmitter and it will work when the SPOT and InReach don’t. The downside—it is one message only. SOS! And a beacon to help them find you. Let’s say you’ve sprained an ankle, and you might need assistance at a side trail, but you’re going to self-rescue out to the trailhead. You have no way of communicating that. (Chances are, though, if you’re on the JMT, sit tight and you’ll find someone with an InReach within the hour.)

SPOT is one-way only, but if does allow you to send a few different customizable but preset messages, allowing you to check-in, say you’re OK but running late, or that true SOS. I’ve found SPOT to have more problems connecting than the InReach, especially with a narrow view of the sky. And isn’t close to the true PLB transmitting power of the ResQLink. Unlike the InReach, communication is one way only, you can’t receive messages.

So, bring a map. Load a GPS app and maps on your phone if you’re bringing a phone anyway. And bring the InReach if you need more flexible or two-way communication.


Addendum: Outdoor Gear Lab has a good comparison of the SPOT vs. InReach vs. ResQLink. Not specific to the JMT, but drawing similar conclusions for more general use.

There are also rental options for these devices from companies such as Lower Gear and Outdoors Geek.


About Mike Rogers

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