Adventure racers, ultra-runners and Ironman competitors all have one thing in common: the quest for a rugged GPS sport watch that'll match the endurance of their own crazy feats of durability.
It's tough to find a sports watch that has a battery life that can contend with the demands of a 100-mile ultra, while still letting you use all of its rich features.
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Yet, while there are inevitable trade offs, some wearables are clearly more capable of going the distance. We've lined up the most fully-featured trackers with the best staying power...
Garmin Fenix 5
With GPS and GLONASS support for fast fix and good tracking accuracy, as well as outdoor navigation features like 3-axis compass, altimeter and barometer, TracBack and Sight'n Go and waterproofing to 100m, Garmin's flagship adventure tracker is a serious piece of kit.
Must read: Garmin Fenix 5 review
But all that'd be nothing without the staying power to back it up. The Fenix 5 promises two weeks of battery life in smartwatch mode, 24 hours in GPS mode and a whopping 60 hours in UltraTrac battery saver mode, although this all still depends very much on how your settings are locked in.
GPS battery life: 24 hours
An oldie but still a solid pick, the Sunto Traverse is a rugged watch that's good for 100 metre water resistance, offers GPS and GLONASS (for added accuracy) plus there's built-in topographic maps to help navigate those tough trails.
Read this: The best outdoor GPS watches
There's also a host of useful cycling and running metrics on board, and even a flashlight mode. It's the battery life that's the reason to pick this one up, though. You can expect up to 100 hours in navigation mode and 14 days when used in standard watch mode. Mighty impressive.
GPS battery life: 100 hours
Suunto Spartan Ultra
A natural successor to the Ambit3, the Suunto Spartan Ultra is also a healthy alternative for those looking to steer clear of Garmin's band of multisport powerhouses.
With this, you'll be able to rock route navigation while also having access to a compass, altitude and even heart rate in the water (up to 100m) when paired with the compatible chest strap.
Read this: Best wearables for triathlon training
But, as always, battery life is factor to keep in mind. And Suunto indicates that its flagship device can offer you 18 hours of GPS with settings not scaled back. If you do decide to go into power saving mode, you'll stretch this out to a healthy 26 hours.
There's stronger devices in terms of battery life that Suunto has in its locker, but with the Spartan Ultra packing in 80 pre-set sport modes, it's an elite addition to any wrist.
GPS battery life: 26 hours
Garmin Forerunner 735XT
The Garmin Forerunner 735XT may not pack the same amount of sensors as some other Garmin devices out there, but it's still a strong option for triathletes and those looking for a wrist companion that can tolerate endurance events.
Featuring many of the same advanced running, cycling and swimming metrics as the Forerunner 935, it's also able to provide up to 24 hours in UltraTrac mode without optical HR, around 14 hours in activity mode with GPS and optical HR and 11 days in watch mode.
And while it may be a bit long in the tooth, the older Garmin Forerunner 920XT is still one of the most fully-featured multi-sport watches you can get your hands on - taking many of the best bits from its siblings and cramming them into one multi-talented swim-bike-run tracker.
GPS battery life: 24 hours
Polar's top end multi-sport timepiece, the V800, is at its best as a running watch but also pairs with cycling accessories to deliver good on-the-bike stats and pleasing, when paired with the right heart rate chest strap, also offers heart rate tracking in the water, a big bonus for endurance swimmers out there.
Wareable verdict: Polar V800 review
There's a multisport mode, which allows you to easily change sports and record complete sessions. For the adventurers and hikers, there's also a barometric altimeter, a magnetic compass, and the ability to get upwards of 50 hours of battery life in a low-power GPS mode.
GPS battery life: 50 hours