COROS has introduced the COROS APEX 4, a watch designed to streamline the previous APEX 2 Pro & Apex 2 Non-Pro versions into a single edition, while concurrently skipping the number 3. Because…umm…never mind that.

In any event, the APEX 4 is a watch that takes the new features found on the NOMAD introduced about two months ago (such as the microphone), and adds additional features like an actual speaker (versus a beeper previously), faster map rendering, and an underwater depth gauge that doesn’t record depth anywhere. And, to the delight of MIP fans everywhere, it retains the MIP-based screen. Oh, and it got more buttons. Woot to buttons!

In many ways, the APEX 4 is designed to somewhat complete COROS’s watch portfolio. And I’d argue, for the first time ever, the purpose in life for the APEX watch in the lineup actually makes sense. In the past, the APEX has always been the awkwardly and oddly priced unit without a clear reason for existence (competitively). Now, it finally has a purpose in life. Don’t worry, I’ll explain that too over the course of this review.

In any event, as always, I’ve been putting this watch through its paces – including on a 70KM single-day trek, to see how battery life holds up in real life, as well as navigation. After all, this watch is designed for long-battery life outdoor adventures. Does it compete?

So let’s get into it!

What’s New:

Nearly three years since the last edition (APEX 2 series), there’s a lot of newness. Of course, COROS is generally pretty good with firmware updates, and thus from a software standpoint, almost everything over the past few years has landed on the COROS APEX 2/2 Pro already. So this list is more about new hardware changes, as well as new features announced today. Got it? Good.

– Added Speaker (for voice calls & audio alerts) – Added new ‘Action’ button (customizable extra button) – Added dual-microphone with voice pins/notes feature – Added ability to take phone calls – Added new weather widget with saved locations – Added street names to the offline maps – Added POI database to offline maps – Added separation of roads & trails to offline maps – Added ‘Record a pin’ geo-tagged voice notes feature – Added depth gauge sensor (very limited though, see notes) – Upgraded to newer 3rd gen COROS MIP screen (more contrast) – Upgraded internal processor – Increased map speed “30x faster” (more on that later) – Increased route storage up to 100 routes – Increased storage to 32GB for all models (previously the non-Pro APEX 2 was 8GB) – Added/renamed satellite modes to have an endurance mode (same battery times as previous GPS mode) – Has WiFi, Bluetooth, and Bluetooth sensor support (no ANT+ sensor support) – Water Resistance rating of 5ATM/50 meters – Does not have new fishing features from COROS NOMAD – Retained MIP display – Weight: 42mm is 56g with silicone and & 45g with nylon band, 46mm is 64g with silicone band and 52g with nylon band – Screen size is 1.3” for the 46mm (260x260px) and 1.2” for the 42mm (240x240px) – Sapphire glass display with titanium bezel (remainder of case is plastic) – Both models have multi-band/dual-frequency GPS (previously only the APEX 2 Pro had it) – Battery life a mixed bag, some of it a wash, some of it a bit higher (see chart below)

As for what happened to the APEX 3? Well, in short, COROS says they didn’t want a scenario where in the future a customer goes to the COROS website, sees a different model named XYZ 4, and then wonders why the XYZ 4 product has a higher number than the higher-end APEX 3. So, they named it the APEX 4. Decoded for simplicity: The only other COROS product that would sequentially be next for ‘4’, is the COROS PACE 3. So, this sorta hints that a COROS PACE 4 is on the way. As for a Vertix? I guess they’ll also have to skip 3 there, and go with Vertix 4. Or maybe just get ahead of the game and call it Vertix 6. Kinda rhymes.

So, here’s the pricing below. Previously, the APEX 2 Pro was $449 (46mm), and the APEX 2 (non-Pro) was $349 (42mm). Now they end up at $429 for the smaller APEX 4 at 42mm, and 479 for the larger APEX 4 at 46mm. So basically, both sizes in price went-up by $30 for the Pro, and by $80 for the non-Pro becoming what is effectively the small APEX 4 Pro.

The unit is offered in two sizes, and two colors, per below. COROS says next month (November), they’ll allow you to order with a mixed black/white band (e.g. band white, case black), but not at launch.

The smaller APEX 4 (42mm) bands are 22mm and compatible with:

– Pace 3, Pace Pro, APEX Pro, and Vertix 1

The larger APEX4 (46mm) bands are 24mm and compatible with:

– NOMAD

When it comes to battery life, there were some changes. Some of it is essentially a wash from before, and some of it is the same. Here’s the key changes:

Basically, they replaced the standard GPS profile with the Endurance profile, but instead of being just GPS-Only, it’s now a blend of All Systems, automatically switching between them. That’s semi-similar to Garmin’s SatIQ, except critically, COROS won’t escalate to dual-frequency, whereas Garmin will. Said differently, don’t use it in really tough GPS environments (e.g. NYC). Meanwhile, that same profile, but with all of the satellite systems enabled all the time (High), does get about a 20% boost over the previous iterations.

The APEX 4 Basics:

In this section I’m going to look at the basic features of the watch, including some of the widgets, activity tracking, sleep tracking, and so on. This will also include the voice calling pieces, though, those are better covered in the video where you can actually hear the audio quality.

First up, you’ve got the buttons and touchscreen. You’ll notice one of the right-side buttons is now over on the left side, and officially named the ‘Action’ button. In theory you can customize this a bit more, and that’s true in sport modes, but less true in the rest of the user interface (such as not being in a sport mode). There’s still the Digital Crown, that both rotates, and acts as a button too.

I didn’t have any issues with the user interface here, and the buttons worked well when I didn’t want to deal with the touchscreen (which…is almost always). The Digital Crown, like most digital crows, can be a bit fiddly with gloves (or if your fingers are really cold). But they are handy when zooming quickly in/out of maps.

In any case, you can tweak the watch face from a slate of watch faces via the COROS App, or a handful on the watch built-in. Here’s two of the alternative ones that are built-in, but again, there’s a gazillion more on the app.

Down from there you’ve got the widgets. These are lightly customizable, and cover a wide array of daily activity stats, training stats, things like weather and notifications, and more.

For example, here’s a weather widget that you can expand out, and get more details about the upcoming…sun. And lack of rain. Or wind. Don’t worry, the next day I’d find both…for an hour.

This is where you’ll see stats like your sleep stats, including HRV status and more. In my testing, COROS had no issues nailing the times I went to sleep and woke up. As always, I don’t do comparisons of sleep phases/stages, because the comparative technology to do so simply isn’t that accurate, only about 80% accurate. Thus, it’s simply not good enough to make any meaningful comparison statements with.

Now, one thing that’s kinda neat you might notice above, is that it shows my sleep at 6hrs and 58mins for the day, and then my actual sleep for the night at 5hrs 1min. How come? Well, because after getting the kids ready, then dropping off the kids at school, I decided to take a nap. 5 hours of sleep wasn’t quite feeling like enough to tackle the day ahead. Thus you’ll notice the two times (overnight + nap) added together equal my total sleep time. Meanwhile, you’ll see my overnight HRV score is specified as within the ‘Normal’ range.

You can dive into that, along with other stats like daily heart rate, etc…

And of course, all of this is synced to the COROS app, where you can look at your stats longer term, or just in more details than the watch might show.

Now, one new feature is the added speaker. Previously, COROS watches have had a beeper, but a beeper can’t vocally do anything. It just beeps (albeit, all sorts of beeps). Whereas a speaker allows it to have vocal sounds (such as when you start/stop a sport, turns, etc…). And most critically for this section, allows for voice calls.

But, this does require a few things:

A) Your cell phone must be within Bluetooth range, and must be paired to your watch B) That the call is inbound, not outbound

That’s because there’s no dialer feature function on the COROS watch, nor any contacts book of sorts. That means you’re effectively using your phone as a speaker/microphone, just like a Bluetooth headset. Thus, this really only works for inbound calls. And, only when it actually works. Repeatedly it doesn’t seem to trigger and simply won’t show an inbound call is coming in. As if nothing has happened.

In any case, when someone calls you, you’ll see the option to answer that call on your watch, and you can accept the call from the watch. In doing so, you’ll leverage the speaker/mic there. The quality actually surpassed by expectations, and is one of the best speaker/mic combos I’ve heard to date on a sports-focused smartwatch, aside from Apple/Google/Samsung.

That said, as I also learned today, it doesn’t have any water ejection mechanism (like most of the others, including Garmin, do). As such, when you go swimming with it, the speaker is mostly useless for the next few hours afterwards, until it dries out.

Sports & Navigation Usage:

Next up is sports usage, which is undoubtedly why you bought a COROS watch. In this case, things are pretty darn similar to the past, just with all the updates rolled into it from the past few years. Though, COROS has been pretty good there, so if you have an APEX 2/2 Pro, then you’ll find very few differences here.

First up, you’ll select your sport mode. There’s boatloads of sport modes covering virtually every sport you’d need, as with the past. You can customize the data pages and data fields here, on a per sport profile basis. This also includes other attributes too, like the Action Button in the lower left corner, in terms of what it’ll do when you tap it.

After selecting a sport profile, you can customize a few things, including structured workouts as well as load up a course for navigation.

The APEX 4 now supports up to 100 routes loaded. Though, annoyingly, it still requires you manually select each route you want to sync, versus just automatically syncing new favorited routes from Strava/Komoot/etc…

The next new feature the APEX 4 has is that speaker as mentioned earlier, but here, it’ll give you various voice alerts in a sport mode. Though, kinda oddly, it’s disabled by default. So you’ll need to enable it, else…well…you’ll sorta miss out on the main new feature.

Once all that’s done, off you go on your workout/activity/suffering.

One of the marquee features that COROS advertised is “30x faster map rendering”. This, despite them adding in various street labels (albeit, at very zoomed/low levels), POI’s, and more. And to COROS’s credit, it’s definitely super fast. You can check it out in the video, crazy quick. Though, I think 30x faster is a wee bit of stretch.

One of the things that becomes really apparent after you start using AMOLED watches, is just how bad MIP is on the map pages especially, in lower-light scenarios (e.g. sunrise/sunset/heavy overcast clouds/forested areas/etc…). Even with the backlight kicks in, it’s still not awesome on the map pages. For the main data pages, it’s largely fine.

In any case, before I forget, COROS has downloadable (free) maps of everywhere you’d want to go. You can simply tap the section of the map you want from the app, and then it’ll connect to WiFi and download it. Super quick and easy.

When you do a lot of trail activity, the single biggest gap between COROS & Garmin/Suunto, is the lack of a ClimbPro like feature. COROS simply shows the total ascent/descent remaining. Whereas Garmin & Suunto will automatically divide up all the climbs/ascents, and show you the distance to each summit, and total climbing left. Here’s an example of the COROS and what it shows, versus the Suunto.


Here, the Suunto shows 3.21KM left on this climb, with me at 85m of 369m on this particular climb, an average gradient of 11%. Whereas COROS just painfully reminds me that I still have about 1,500m of climbing left today (Suunto also shows that too, but on a different page).

The next feature the APEX 4 has, comes from the NOMAD, which is voice pins. Here you can create little voice memos/notes, which are automatically geotagged for later reference.

You can then see these in the app afterwards (see the , including an automatic translation, which is pretty slick.

Admittedly, I keep forgetting this feature is here. Mostly because I’m not really sure what to do with it. I’m sure someone appreciates it, but it’s just not something I’d use very often.

Moving along, once your workout is done, you’ll see all the details in the workout summary, visible on both the watch and the COROS app.

Meanwhile, COROS also tracks various training load and recovery stats too. For example, it’ll predict your upcoming race results/potential, though, this does depend on giving it lots of data across a variety of intensities. Notably, interval workouts, and specifically in the case of COROS, flat terrain road workouts. In my case, I don’t have a lot of those, as I’ve been doing more trail running lately.

They also have training load, though, annoyingly this still resets every Monday. Other companies do proper 7-day trailing load. And COROS recognizes this, and even has 7-day trailing load in their app, but that’s not really where I want to look. So you can see here, that 656 training load value is merely my Monday/Tuesday combined load (when I took this photo), versus the last 7-days load.

COROS talked about changing that, after the NOMAD was released. But sadly, it hasn’t happened yet.

The Depth Gauge:

Next up, COROS added a depth gauge to the COROS APEX 4. Though, there’s whole bunch of caveats here at this time. IN talking to COROS, it became clear this was more a case of ‘let’s stick the hardware in now, and figure it out later’. And to COROS’s credit, aside from mentioning it in specs and such, they don’t market it in any other way.

So, bullet-point style, a whole slate of things to note:

– At present, there is no specifications on how deep the depth gauge actually measures to (e.g. capped at 40m, 100m, etc…) – COROS has not sought any depth gauge certification for the depth gauge, the watch hardware as a whole, or the watch software. Typically this would be EN13319, and/or ISO 22810:2010. – There is no snorkeling, scuba, or free diving type modes/activity profiles – COROS is clear to NOT use this for any of those activity that requires accurate depth data – The data may be recorded somewhere, but it doesn’t show up in the app afterwards at present

With all that said, in order to get the depth gauge to work, it’ll only show data in the Openwater Swimming profile. And within that, only if you actually configure/add the data fields for it (by default, they aren’t shown). There’s a few data fields you can add, including current depth, max depth, current water temp, and average water temp.


Once you do that, you can go off and swim. Or snorkel. Or whatever it is you do.

When you do so, you’ll see the current depth displayed. In my testing down to 5.5 meters (the max depth in the area I was in, my bay only has a max depth of about 7.5m, and some large boats were out playing in that area today), it matched both the Garmin Fenix 8 Pro and Apple Watch Ultra 3. Both of those device have certified depth gauges in them, which confirms to various international standards on testing of said gauges.

However, an example of one of the COROS quirks is that while there was a Max Depth data field, that appeared to reset every time I came to the surface. While many dive/snorkeling watches have a ‘Dive Max Depth’ data field that operates similar to a Lap field (each short dive you go down, it resets), this doesn’t specify that difference. Certainly, it’d be a handy field to have, but as of right now, doesn’t appear to be labeled correctly.

And of course, as noted earlier, none of the depth data is shown in the COROS app afterwards. I’m sure it’s saved somewhere, but…just not a place I can see.

In any event, I’m guessing this is COROS dipping their toe into the water of snorkel/freediving/scuba diving. This allows them to low-risk test how well this hardware component handles long-term, before likely lighting up something like a full free diving/scuba profile on a certified dive in a Vertix 3/4 series device. And just to be clear, I’d except depth gauge certification in any device that claims scuba or free-diving functionality. If it doesn’t, I’ll give it a VERY hard time here.

Until then though, it’s fun (and fine) to play around snorkeling with it.

Accuracy (GPS & Heart Rate):

In this section I’ll look at accuracy of the heart rate sensor, GPS, and some elevation data too. Heck, even a bit of battery burn.

First up, let’s look at a relatively simple tempo run. Or tempo-ish. This is compared to the HRM-600 chest strap, the Polar Loop (on a bicep band), the Whoop 5 MG (bicep band), and the Google Pixel Watch 4 on the other wrist. I have no complaints here, obviously, it’s perfect.

And likewise, this was super-easy from a GPS standpoint, and you can see the three GPS watches all aligned without issue:

Ok, so let’s look at another easier one, before increasing difficulty, this time an indoor trainer ride. Again, no issues here on the COROS APEX 4, which is to be expected. After all, indoor trainer rides are about the easiest thing for optical HR sensors, given there’s virtually no vibrations/movement/etc…

So, let’s kick it up a notch, and head back outside for a 2hr trail run. This has some sharp/steep climbs. Looking at the heart rate here, things are mostly pretty good:

(The drop you see there on the chest strap is due to how Garmin toggles off sensor connectivity when it goes to send a satellite message on the new Fenix 8 Pro.)

I see one brief section where you see the two wrist-based optical HR sensors struggle, whereas the chest strap and Whoop (bicep band) hold together a bit better, but that’s pretty much it.

Anyways, looking at the GPS side of things, again, at a high level it looks good:

And at first, when you look at the track at a medium level, it looks good as well:

But as I zoomed in, I noticed that the APEX 4 is overly smoothing some of this trail run. These are very real/legit little switch backs on this trail, that are being kinda wiped out here.

We see it again in other areas, where the APEX 4 appears to be overly smoothing some of this.

As a result, we see the APEX 4 being a bit shorter than the others on these sorts of activities. COROS probably lucked out on this particular example, because the Garmin Fenix 8 Pro and Apple Watch Ultra 3 made a few GPS errors that skewed their numbers too.

So I then went and looked at my 70KM hike that I did, which included tons of mountain time.

And…ummm…yikes. It’s just playing ‘connect the dots’ in the mountains.

Here, another section (in this section, the Fenix 8 Pro track is briefly missing, as it took a 2KM vacation to send a satellite message, a bug supposedly fixed in a firmware update about 10 days ago). But, as you can see with the COROS, it’s like a bad smart recording from days of past.

What’s fascinating about this though is that the final distance on the COROS is near identical to the others. My guess here is that they’re using the stride-based distance in some capacity here. But given the COROS was set to ‘Max’, I don’t understand why the GPS looks so bad here.

Like, this is really bad. You can skim through the full data set here.

On the bright side, elevation accuracy was good:

Next, two more quick sets. Next is an outdoor road-ride I did. Here, looking at the heart rate first. Yikes, this is hot-mess territory, mainly after the crash, when my HR was substantially lower. This doesn’t surprise me though, outdoor cycling continues to be very challenging for optical HR sensors, though most do better these days.

And then from a GPS standpoint it was spotless on the sharp descents.

Which got me thinking: Why on earth was the GPS so bad on some trail runs and hikes, but fine on other road runs and road rides? And then I realized: All the workouts with navigation (route following) enabled, it was hot-mess territory. If that wasn’t enabled, it was fine. There’s clearly some sort of issue with the processing power when a route is loaded, causing significant GPS accuracy issues.

And lastly on accuracy, looking at an openwater swim from earlier today – it wasn’t bad, but also wasn’t great, as it’s undercutting a bit, as you can see below:

Ultimately, looking at heart rate accuracy first, with the exception of outdoor road riding – this was very good. On the GPS side, per above, it’s great as long as I’m not doing some sort of navigation, in which case, the GPS accuracy seems to degrade substantially. Hopefully they can fix that soon.

Finally, looking at battery burn, here’s how things looked on that 14hr hike with navigation enabled. In this case, I was mostly on non-map data pages for all units, save for turns, where I’d look at the map on all units at once. You can see here the COROS APEX 4 (MIP) & Suunto Vertical 2 (AMOLED) were near identical at about 2% an hour the entire time. All watches were configured for dual-frequency/multi-band GPS.

In the case of the Fenix 8 Pro MicroLED, the big shift there in battery life is when I changed the LTE setting from “Always On” to using the cellular on my phone instead. That massively changed the battery life here.

But as for the COROS, that means it actually did better than the battery claims (which are ~40hrs in this mode), coming in instead at ~50hrs of battery life. And that claim doesn’t even include navigation, so this is a solid job.

Wrap-Up:

When the original COROS APEX 2 & 2 Pro came out, they were priced in a weird spot. Back then, at $499 for the APEX 2 Pro, it was a mere $50 less than the Garmin Forerunner 955 – an absolute powerhouse of features, functionality, accuracy, and the entire Garmin platform behind it. Simply put, the APEX 2 Pro got slaughtered by it. So much so that COROS eventually lowered prices on it.

But now, the tables have turned. Garmin’s ever-increasing prices over 2025, combined with not putting maps on sub-$500 watches, means that COROS (and Suunto/Polar) are in a much better spot in the sub-$500 realm than ever before. With both the COROS NOMAD at$349and the APEX 4 at $449 having full mapping, dual-frequency GPS, and now the speaker and microphone on the APEX 4. Sure, it doesn’t have other features from the Garmin ecosystem like Connect IQ apps, and some of the polish of that platform at large. But it does have free offline maps, and for a lot of people, that’s a big deal.

And more than that, it starts to fill in the gaps in the COROS lineup. That lineup starts with the COROS Pace 3 at $229, then the Pace Pro and NOMAD at $349, followed by APEX 4 at $429/$479, and then finally Vertix 2S at $699. Obviously, the Vertix is looking pretty long in the tooth at this point, especially given the Vertix 2S was barely a minor spec bump. Point is, they have not just a clear increasing of price vs features, but different options at different price points. The trick will be to maintain that pricing as they go forward with a Vertix 3/4, in order to undercut Garmin’s increasing prices. Just like before, when COROS tries to compete head to head with higher-end watches, it doesn’t end well. Instead, COROS is most deadly when they undercut on pricing and deliver strongly on features (e.g. Pace 3).

In any case, I’m sure plenty more to come. With that, thanks for reading!

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