Swimmo comes with IntensityCoach™ and PaceKeeper™ that offers encouragement, and guidance via a series of vibrate alerts to inform you when you need to speed up or slow down. In addition, Swimmo utilizes patent-pending "Rotate&Tap" technology that enables the wearer to access functions via gesture, so no need to deal with fiddly buttons while submerged.
The accompanying app enables the user to set goals based on calories burned, distance, and duration. It also enables swimmers to share their data via social media, as well as with other Swimmo owners, via a league table.
According to the makers, Swimmo doesn't need to be tethered to a smartphone to work, however the stored data will need to be synced to a smartphone via Bluetooth, or presumably it will be lost forever. Compatibility with HealthKit, RunKeeper, Strava, and other popular fitness apps is in the pipeline.
Other swim trackers do exist such as Garmin's Forerunner 920XT, Swim Watch, and the Xmetrics but if you want to grab a Swimmo, head over to Kickstarter and pre-order one for $179. International shipping is available and the estimated shipping date is October 2015.