The best watches for thru-hiking: the ones that get to the next town without your power bank

The direct answer

Thru-hiking inverts how watches are normally judged. Heart-rate accuracy, training load and race predictors are irrelevant. What matters is the amount of electricity the watch takes out of a battery bank you are carrying on your back, and how many grams it adds on your wrist.

That reduces the whole category to one question: can the watch get from town to town without being plugged in? On a long trail, resupply is typically four to six days apart, and your bank is already committed to a phone. A watch that wants a charge every five days is a watch that costs you capacity you needed for navigation.

A solar lens solves that outright, which is why four of these five picks have one.

Think in resupply intervals, not hours

Here is the translation that makes the spec sheets useful. A thru-hiker wearing a watch all day in daylight is the exact user Garmin's solar figures are written for: three hours a day at 50,000 lux is bright overcast to full sun, which is what you get walking ten hours a day in the open.

At that exposure, Garmin states the Instinct 3 Solar is unlimited in smartwatch mode and unlimited in max-battery GPS mode, with up to 260 hours of GPS-only. Those are the only numbers on this page where the honest answer to "how often will I charge it?" is "you will not".

If you want the watch recording a GPS track for the whole trail rather than just telling the time, read the second number instead of the first. The Enduro 3 states up to 320 GPS hours with solar charging and up to 120 hours with multi-band SatIQ, which is roughly two weeks of all-day recording in the lower-accuracy mode. The fenix 8 Solar 47 mm gives 67 GPS-only hours and 92 with solar, which is a few days of all-day recording and then a charge.

The picks, side by side

The Instinct 3 Solar leads because it is the cheapest watch here and the only one whose battery answer is a word rather than a number. It is also the one with the fewest things to go wrong: a monochrome MIP display that costs almost nothing to leave on, physical buttons, 10 ATM, a build Garmin states is to MIL-STD-810, and a flashlight with a red mode that doubles as a camp light. What it does not have is maps or a sapphire lens.

The Enduro 3 is the thru-hiker's flagship and the better watch if the budget allows: 90 days of smartwatch battery, 320 GPS hours with solar, a sapphire lens, a 51 mm titanium bezel, and — the detail that matters most on trail — 63 grams on its UltraFit nylon band. That is lighter than the 62-gram Pro Trek is heavy, for a watch with maps and a battery measured in months.

The fenix 8 Solar in 47 mm is the pick if you want full mapping on a medium wrist and accept shorter figures than the Enduro. Sapphire, a titanium bezel, preloaded TopoActive maps, a 40 m dive-rated case and leakproof buttons. It is the most capable watch here and the one that most needs a plan for charging.

The Suunto Vertical Titanium Solar is the lightest sapphire solar watch anyone makes at 74 grams, with a Grade 5 titanium bezel, 100 m, and Suunto's own figures of 60 days of daily use with solar and up to 140 single-band GPS hours with solar. It is a strong alternative if you prefer Suunto's simpler interface; the comparison is in Suunto vs Garmin.

Weight, and the nylon strap trick

Thru-hikers count grams, so here is the single cheapest change you can make: swap the silicone strap for nylon.

The published figures make the point. The Enduro 3 ships on a nylon band at 63 grams. COROS publishes its weights both ways and the difference is consistent: the VERTIX 2S is 87 grams on silicone and 70 on nylon, and the NOMAD is 61 on silicone and 49 on nylon. That is a 15 to 20 per cent saving for a few dollars, and nylon also dries, does not trap sweat against skin for weeks, and does not crack with UV the way cheap resin does.

The strap-material argument in full is in resin vs steel cases.

Do you need maps on a marked trail?

Mostly, no, and this is where a lot of money gets wasted.

A marked long-distance trail is navigated with a phone app and a paper or digital guide. The watch's job is to answer the questions you ask twenty times a day without taking a phone out of a hip pocket: what time is it, how far have I come, how much climbing is left, when does the light go, and is the pressure dropping.

That is an ABC-and-GPS job, not a mapping job. Every pick here does it. Maps earn their place in two situations: off-trail alternates and bail-outs, where seeing the terrain around you matters; and winter or fog, where you cannot see the next marker. If either applies, buy the Enduro 3 or the fenix 8 Solar. Otherwise the Instinct 3 Solar does the actual work for a fraction of the price. The mapping options are compared in best watch with offline maps and Garmin watches with topo maps.

The case for no GPS at all

It is a better case than it sounds, and the Casio Pro Trek PRW-61 is here to make it.

62 grams, 51.0 by 47.4 by 14.7 mm, 100 metres, a biomass plastics case, and the direction, pressure, altitude and temperature sensor set with radio time calibration and a double LED light. It runs on Tough Solar, which Casio rates at about six months of reserve with no light at all, and it has no charging port, no firmware, no app dependency and nothing to go unsupported.

For a hiker whose phone handles navigation, that is arguably the correct instrument: the lightest option here, the only one that genuinely never needs power, and the one that will still work identically in fifteen years. The trade is that a barometric altimeter drifts with the weather and needs calibrating at known points, which is covered in ABC watch explained.

The decade pick

How to choose a thru-hiking watch

1. Decide whether you are recording a track. If not, any solar watch here lasts the whole trail. If you are, read the GPS row rather than the smartwatch row and expect to charge.

2. Insist on solar, or accept the power bank cost. Every charge your watch takes is capacity your phone does not get.

3. Prefer a MIP display to an AMOLED. Reflective screens get more readable in bright light and cost almost nothing to leave on, which is why the long-battery picks all use one. See MIP vs AMOLED battery life.

4. Weigh it with the strap you will actually use. Nylon saves 15 to 20 per cent over silicone and dries out.

5. Check the sunrise and sunset data. Knowing when the light goes is the most-used feature on a long trail. The Instinct 3 provides sunrise, sunset and civil twilight plus moon phase from GPS position; the Casios compute sunrise and sunset too.

6. Buttons, not a touchscreen. Rain, gloves and sweat make a touchscreen a liability.