Suunto Ambit2 Trail Test

Original Review date: July 2015. Tested with Garmin HR Strap and 1.5 – 2.0.11 firmware (updated Dec 2015)


A solid, conservative, accurate offering that simply works. It doesn’t exaggerate and it won’t leave you in the lurch. It lacks the suite of features offered by some competitors, but this might also be seen as an advantage by some if you like the KISS principle. Masters-plus trail runners will need their reading glasses and hearing aids turned up as legible screen options are limited and there’s no vibrate alert. Also map making adventure runners are let down by an inability to import/export waypoints. The high accuracy battery exhaustion trail test put the Ambit2 a few minutes short of the magic 14hrs.

A current model round-up can be seen here, and the testing methodology is here

What kind of trail runner is it good for?

Someone seriously into trail or ultras who doesn’t want any distractions. Easy to use, accurate, downright reliable, with no fancy smartphone features. You know who you are.

What should you expect as a long term running companion?

An extremely faithful, if unexciting, companion. Without all the fancy features of it’s competitors and new models you might be tempted to ditch it, but you’ll probably regret it, as its performance in heavy trail conditions currently appears unmatched. That said, limitations and design issues (display, charging, vibrate, waypoints) will try you from time to time, and if you have to suffer though any decent Movescount/Movelink outages things will get rocky.

Good Stuff

The Ambit2 shines when GPS conditions get tough. Though already decent when the going is easy, the watch’s performance holds up better than all others when the environment really deteriorates. Positional accuracy, distance, and elevation are all among the best of the models tested. Reliable plus, no horrific data days, no resets, no lost data, it sets a pretty high standard. Battery life on both high accuracy and down-sampling modes are good. Breadcrumb navigation allows waypoint proximity alerts.

Bad Stuff

Lack of vibrate alert, data/charging-clip design, tiny secondary display fields, and lack of proper waypoint management top the list. As data transfer technically is possible via ANT+ it’s a pity nobody developed a mobile app (especially as a six year old Garmin FR310XT can upload via Android). The locked-down Movescount Suunto Apps are certainly an annoyance, be nice to see Suunto open up a little to get a more vibrant niche developer community generally. Historically both the Movescount webservice and Moveslink2 have been a little unreliable, though 2015 has been solid so maybe that’s all behind us. Navigation is still pretty basic, distance and ETA on waypoints that respect the plotted course distance would be good.

Plea to Suunto

Vibrate alert please, a new clip design, and make the display options a little more flexible so your older trail runners can actually read it while running trail. Please do more to encourage 3rd party developers to move things along in terms of direct watch interfacing (mobile or desktop) and on watch apps – maybe a bit late on the mobile side given the Ambit3 . Navigation could be a bit more helpful, and the waypoint lockdown (can’t import or export from Movescount) is frankly unacceptable for an adventure GPS watch this capable.

Formal Testing


So far Ambit2 formal trail testing has covered over >150km on 20 separate days on the surveyed courses (repeated testing is vital to capture variation). A number of the activities were also specifically planned to assess the impact of poor satellite coverage via tools that give Geometric Dilution of Precision. Potential GDoP was logged for every activity to better make comparisons across models.

The GPS pool against which the Ambit2 was tested included the following models: Garmin fēnix 3, Suunto Ambit3 Peak, Polar V800, Garmin FR310XT.

During testing multiple GPS devices are carried as a means of validation, if all units have a bad GPS day then a tin foil hat is donned. Though some days with poor GDoP potential saw all units a little degraded, no testing days saw GPS chaos across all models.


The positional accuracy of the Ambit2 was impressive across all conditions encountered. In unobstructed GPS conditions the median offset was 1.6 metres (mean 2.0). The Ambit2 also had the least degraded performance in limited relative to its clear GPS conditions. Median offset in limited conditions was 1.9m (mean 2.4m).

Ambit2 distribution of accuracy against surveyed courses
Ambit2 distribution of accuracy against surveyed courses

This performance in limited conditions was further demonstrated on a difficult conditions course (heavy tree cover, steep terrain, gorges) where it was the best performer of any model tested so far. Repeats of the 8km circuit had a median relative offset of 4.4m (mean 5.5m) with 16% of points greater than 10m. These solid results in poor GPS conditions were also repeated in the other times where multiple watches were used.

Variance in accuracy over testing was solid meaning that not only was the average error low, but also stable. There were no instances of really bad GPS days so accuracy appears pretty predictable.


Assessing true distance accuracy is not easy in trail conditions. GPS measured distance is dependent on positional accuracy and sampling rate. Unfortunately errors in positional accuracy can both increase and decrease distance via corner cutting and random scatter, and both are common in trail conditions. As these can cancel each other out an inaccurate track can still give spot on distances. A third type of error, shadowing, where the track runs parallel generally has little effect on distance unless it’s waaaayy off.

Give the positional performance of the Ambit2, you’d expect the distance accuracy to be pretty good, and it is. On average it records over 98% of the measured course distances, and on its worst day still came in at 97%. On any given day you are looking at a 65% chance of recording was within 1% of the actual distance. With Ambit2 distances always slightly running short in trail conditions (you won’t get a true distance by averaging a bunch of them) it looks like Suunto are playing it conservative with filtering. From a training perspective we kind of like the fact that the Ambit2 ran close to but never exceed 100% of the (surveyed) course distance.

In outings that tested challenging GPS condition behaviour (ie. typical NZ bush conditions) the Ambit2 came in around the expected/plotted distance. Though the true course distances weren’t known, the trackpoints between laps were consistent, the track followed contours and features, and were within the envelope of other models, so we’ll call it the winner.

Track Appearance

The sampling rate on the Ambit2 is a little less than the ‘best’ setting of the Ambit3 and 1 second setting of other models. While the actual trackpoint accuracy isn’t really of practical difference between the Ambit2 and Ambit3, the lower sampling rate may partially account for the Ambit2’s consistently shorter distances over the newer model.

Visible random scatter was pretty contained. Conspicuous track shadowing was minor or absent in all but the most challenging GPS conditions, and most commonly seen where a course would run parallel to hard steep/vertical surfaces. In difficult GPS condition trail events where both the Ambit2 and Ambit3 were present, the Ambit2 actually edged out the Ambit3 with respect to apparent shadowing and random scatter.

The trackpoint cloud image below shows the density of recorded positions from all recorded runs against part of surveyed course. Both the limited (track on left) and relatively open (tracks on right) sky view conditions generally depict nice, dense, symmetrical distributions of points near the track. The measles-like spotty effect are at least partly the result of running the Ambit2 on reduced positional sampling (10sec) rates on a few outings.

Ambit2 trackpoint density against surveyed course
Ambit2 trackpoint density against surveyed course

Overall, tracks were well detailed and responsive to rapid changes in direction. In short, trail behaviour was first-rate.


Elevation was tested with the FusedAlti setting on, this reduces the amount of barometric drift by quite a lot. Sure, it’s not perfect, but it’s enough not to be jarring when browsing the watch’s elevation plot. Regardless of FusedAlti it’s always best to manually calibrate elevation at the start of a run which is easy do.

Elevation range, when calibrated at start, is good. Total climb on the surveyed course was good, coming in at an overall average of just over 89%. Variation was also pretty good, on the worst day it came in at 79% and maxed out at 97% (ie. not overestimating, just like distance).

Note: The survey course probably is a bit tough on GPS watches with respect to elevation with lots of rapid 10-30m climbs/descents. Watches would probably perform better on longer more pronounced climbs/descents.

Battery Saving Data Recording

The Ambit2 can be set to sample GPS at 10 or 60 second intervals to save battery, though all other sensors continue the ~1 second updates. Without a footpod, the courses obviously will come in short. How short depends on how fast you are moving and how twisty the course is.

However, as the Ambit2 will update pace and distance from a footpod, its possible for the watch recorded distance to be comparable to the most accurate GPS setting. A calibrated footpod is said to be 99% accurate in ideal (road) conditions. The Ambit2 has shown itself to be a little over 98% accurate distance-wise over mixed, but not overly difficult, trail conditions. Both footpod and GPS accuracy degrade under tougher terrain conditions, so until we see some data or do some mixed terrain footpod testing ourselves, it’s moot and we’ll call it a draw.

While the watch recorded distance may not be impacted by footpod enhanced lower GPS sampling, a few things are. First, Strava works from the GPX data (ie. GPS positions) and it doesn’t respect your footpod, so it’s going to stiff you in terms of distance. Second your GPX track isn’t going to be as detailed.

Third, and most critically, the Ambit2 navigation doesn’t let you use reduced GPS sampling. If you choose an activity mode that uses reduced sampling and then turn on navigation to follow a course, the Ambit2 reverts back to high battery burn GPS mode. You can turn on navigation on only in times of need, but it’s a bit of a pain (you have to remember to turn it off after – and if you are on a 20hr mission your memory is not always the best).

Functional Tests

Data Syncing and Sharing

You are stuck with a cable to sync via a computer with the Ambit2 using Suunto’s Moveslink2 software. No third party mobile development able to suck the data out via ANT+ as with older Garmin devices. While Suunto, like the others, only support Windows and Apple operating systems, some keen enthusiasts have developed an OpenAmbit application that works on your Linux box. This was a bit of a saviour for our Ambit2 owner back in 2014 when the official Moveslink2 software experience a period of pain, it basically stopped working on multiple Windows computers for some weeks.

Once the Moveslink2/OpenAmbit software sucks the data off your Ambit2 it sits in a folder in the SML format which is a flavour of XML (like GPX, TCX, KML). This leaves it able to be picked up by other desktop apps (eg. SportTracks) that recognise the format. The Ambit2 watch itself is invisible to the computer and other applications (ie. it doesn’t appear as a mounted device).

The Moveslink2 app also syncs your data to Suunto’s Movescount website, and watch settings back from the website to your Ambit2 (more on this in the general usability section). The Movescount site allows you to sync out to a number of other sites like Strava and Training Peaks. You can also export individual activities in various formats including GPX, FIT, and TCX.

A third party tool exists (MXActivityMover) that let you upload Garmin Connect activities (and TCX) files to Movescount for a reasonable one off license fee. Nice if you want to keep your stuff together. Haven’t seen any officially endorsed service that will suck your Movescount activities out in bulk, though it appears to be possible. And if you sync from a single computer all the data is there in SML files).

Navigation Functions

Creating a breadcrumb course is easily done via the Movescount site using either Google Maps or OpenStreetMap. Both have an auto-follow roads function when drawing your course, and with the OSM version this includes trails. You can also import GPX files to Movescount if you’ve already got the course (though not any waypoints associated with the course).

And regarding waypoints (points of interest) there are two types which are managed and used separately – waypoints on a course and standalone. Course waypoints must be part of the course and only visible when navigating the course. Standalone waypoints are just as they sound.

You can create waypoints via Movescount or on the watch itself (if you know the coordinates). Annoyingly the standalone waypoint creation map is only via Google Maps which is terrible for trail detail. And you can’t export the waypoints you’ve collected on the watch at all, which makes OpenStreetMap editing or waypoint sharing painful/impractical. Seems like a big functional gap to us.

You navigate to a selected standalone waypoint by line of sight bearings and distance, then manually select the next waypoint to navigate to if required. Unfortunately, when navigating a course there is no functionality to give distance to go or ETA against the course itself.

And for a fully feature mountain adventure type watch, strangely there’s no elevation on waypoints or routes.

Oh and turning on navigation stops any GPS power saving so you are back to a 12-16hr battery life. If we use a map and compass we don’t check it every second, so not sure why navigation forces 1sec GPS updates where I’ve set the activity to update less frequently. Though an update to current position via a button press might be good when we are seriously disorientated.

Pacing Functions

The Ambit2 doesn’t actually doesn’t have any pacing function as standard, but plenty are to be found as watch apps via the Movescount site (see the General Usability section for Apps rundown). The two types of pacing we’ve used are constant pace, and race time. Constant pace is what it sounds like, it measures your time or distance ahead/behind of where you’d be running at that set pace.

Alternatively race time is great for an actual race, these apps basically forecast your finish time on the basis of distance to finish and some kind of weighted pace function. You start running and it’ll give you an estimated race time if you keep it up – saves trying to do pace arithmetic during a marathon.

The problem with both of these types of pacing is that neither respect the changes in terrain you are likely to face on the trail. If your finish has a big hill at the finish, you’d better be banking some time and these kind of pace apps won’t help you with that. As far as we know there are no Suunto apps that allow for variable pace, either synthetic, or past performance which would be much more useful on the trail.

Battery Run Down

Set to 1 minute GPS updates the battery had 66% remaining after 18.5hrs of recording on 3 day climbing trip. On another trip where best accuracy was on for 4:30hrs and 5 second GPS updates for a further 9hrs, battery remaining was 45%.

The high accuracy battery exhaustion trail test saw the Ambit2 die after 13:50hrs (on the box specifications said 16hrs). The test was run in warm, mixed trail conditions with a HRM and GPS setting set to best, battery was charged to 100% a few hours before the start of the run. Also worth noting the Ambit2 was two years old at time of testing.

Standard Feature Set

General Trail Running

  • GPS accuracy under canopy : Excellent
  • Consistent GPS performance : Yes
  • Rapid GPS Acquisition: Excellent
  • HRM : Yes
  • Cadence option: Yes
  • Battery 8hr (with HRM) : Yes
  • Barometer (for altitude) : Yes
  • Basic breadcrumb and waypoint navigation : Yes
  • Vibration alerts : No
  • Trail legible display: Poor
  • Open data access : Yes (except waypoints)
  • Sensor Standards Compliant : Yes

Ultra Feature Set (as per trail running plus)

  • Battery 14hr+ with HRM and high accuracy recording : Very close at 13:50hrs
  • Battery 24hr+ with HRM and down-sampling : Testers required
  • Electronic compass : Yes

Nice to Have Features

  • Mobile uploads (Android/Apple) : No
  • Cadence (without footpod) : Yes
  • HRV (R-R) recording with recovery estimate/test : Yes
  • Footpod GPS override option : Yes (always overrides when footpod present)
  • Basic interval workout ability : Yes
  • Pacing function : Yes (via apps)
  • Position/waypoint autolapping : No
  • Feed/drink or run/walk timing reminders : Yes (via apps)
  • Everyday watch : Yes
    • Activity Tracking : No
    • Mobile Notifications : No

Non-Tested Core Features

While functions like heart rate and cadence are core, we’ve got no means of objectively testing them.

Nothing out of the ordinary seen on either heart rate or cadence behaviour. Running with a footpod showed no obvious difference to that of running with the Ambit2 alone regarding cadence. The footpod can and should be manually calibrated for distance. As was mentioned in the battery saving section, the performance of the footpod in trail condition is a bit of an unknown and should be tested in various conditions at some point.

Hard to assess the recovery estimate data provided by the Ambit2, sometimes we felt better than it suggested and other times it took us a bit longer.

General Usability

Audible alerts are pretty clear, though there are plenty of situations where we don’t want or can’t hear audible alerts (wind noise, bunch runs with everyone beeping, winter jackets, old age). The lack of a vibrate alert is puzzling, even if it does impact battery life.

The screen is reasonably sized but a little washed out compared to some. We found that while the dark display looks snazzier, the light display is more legible in daylight (unless you accidently hit the backlight button). Conversely the dark display works better at night with the backlight.

The layout only allows for one large figure on display at any one time, with one or two supplementary fields. All of us have trouble reading the tiny fields at the top and bottom of the watch when running race pace, trail, or after 12hrs on the feet. It would be nice if layout was a bit more flexible to allow larger font sizes.

Time to GPS fix is quick as you’d expect for a unit that pre-caches satellite availability, when recently synced and in the same area as last used we talking a few seconds. Adhering to the ANT+ standard we can use any old sensor we find lying around without issue. All good.

What definitely is not good however is the data/charging-clip design. It had to be replaced after 8 months as the contact pins became permanently recessed. Evidently this seems to happen a bit, though Suunto did a warranty replacement without too much fuss. Not sure why a watch with great build quality is shipped with such an average charger design.

A feature of the Ambit series is the antennae ‘wing’ built into the strap, we’ll take a punt here and credit that as part of the reason it fares so well in terms of accuracy – so it can stay. Buttons are pretty logical, and are context dependent, doing different things on different screens and modes in a pretty direct way.

Setting up the Ambit2 is done via the Movescount site which is then synced back to the watch via a computer. On the one hand this makes watch setup fast and easy compared with fiddling with the watch itself. On the other hand you need a computer, and an internet connection to do it. Though the computer based setup of the watch is great, it would be great to leverage that a bit more. For example there’s no copying or moving watch screens within or between sport modes.

Those who’ve been using the Ambit2 for a couple of years will know that historically both Moveslink2 (the computer syncing application) and the Movescount site have had a few issues with reliability. During formal testing we’ve had no issues but the watch owner fondly recalls the multiple day outage of Xmas 2014 (and the aforementioned issues with Moveslink2). Hopefully Suunto have upped their game on server resilience and app reliability.

Another aspect of the Ambit2 that causes a bit of pain, if only very infrequently is the fact that firmware updates wipe the watch history. As the Ambit2 only had three updates it wasn’t too disruptive. It’s also worth noting that the performance of early Ambit2 firmware releases were solid performers, the updates simply added new features.

Though the ‘out of the box’ function list is a little basic when compared to some GPS watches these days, the watch Apps available via Movescount pad things out somewhat. Many useful if not core functions are provided via app by Suunto and Joe public alike. Good examples being race pacing, current incline, and tides (for coastal running). Though annoyingly the Suunto developed apps are locked down and unable to be adapted by mere mortals. If you don’t live in a region covered by the tidal app, tough (unless you can figure out how to write it from scratch). The user apps by contrast generally have their code public so it can be adapted as required.

Like shoes and backpacks, comfort is a personal thing – try before you buy.

Long Term Verdict

After 2500km of use the Ambit2 has been more reliable than Waitakere mud (and it’s always muddy in the Waitakere’s). We’ve never had an issue with freezes, resets, or data tracks that were clearly way off base. We’ve done plenty of high intensity trail races, a number of ultra-distance outings (up to 14hrs), the odd hike, and a good year’s worth of run and bike commutes.

Long term issues we’ve noted are the charging clip failure as already noted, and wrist strap band breakages seem to be commonplace after a few years use (two from the group  have had issues).

Other than that simply nothing to complain about in terms of it doing what it says it’s going to do.