Garmin has really made their mark with the Garmin 255s Music.  The “s” is the smaller, 41mm sizing. Purchase the watch for running, but it is great as you transition into triathlons.  This is the watch is an update and replacement to the 745 and 245 and has a battery life that can keep up with all your adventures.  The battery life is 30 hours sans music.  With its sleek design and 1.7 oz weight, you’ll almost forget you’re wearing Forerunner 255 Music — even when you’re asleep.  This watch is geared to the athlete who wants to do it all. There are 30+ built-in activities, including the triathlon and open-water swimming profiles — new to the Forerunner 255 series. For races and brick workouts, transition to the next activity with a single button press.