With up to 120 hrs. of continuous tracking, the Suunto 9 Baro is built to last—just like you. It's been tested to withstand extreme conditions, so you can boldly pursue your goals. Suunto intelligent battery technology sends smart reminders based on your activity history to help ensure you're fully charged for your next outing If the watch notices you are running low on battery during an exercise, it will automatically suggest changing to a different battery mode Performance mode (up to 25 hrs. of battery life) provides the most robust data and best GPS accuracy Endurance mode has 40 hrs. of battery life with integrated wrist heart rate tracking on, or 60 hrs. when paired with a Bluetooth® Smart heart rate belt (sold separately) Ultra mode takes less-frequent GPS readings and deactivates wrist heart rate tracking and Bluetooth® connectivity in order to boost battery life to up to 120 hrs. FusedTrack™ combines GPS and motion-sensor data to improve track and distance accuracy for ultralong runs without significantly compromising accuracy Integrated wrist-based heart rate tracking eliminates the need for a chest strap (though you can use one for longer activities to save battery power) Supports more than 80 activities, using GPS data and the barometric altimeter to track time, distance, pace, elevation and ascent/descent Program waypoints or create a breadcrumb trail Powerful training summary on the watch includes graphs and lap tables 100 meters of water resistance means you can wear this in the pool; swim functions include pool and open-water pace and distance, automatic intervals and interval lap table Integrated storm alarm, weather trend data and sunset/sunrise times help you make informed decisions when outdoors Pair with your iPhone® or Android™ device to receive notifications on your wrist Scratch-resistant sapphire crystal glass and stainless-steel bezel hold up to tough environs Compatible with apps like Suunto Movescount, Strava, TrainingPeaks, MapMyFitness and more