In a team managed by Martin Truijens coach of the Dutch National swim team in Amsterdam algorithms are developed and validated that monitor stroke type, exact lap time, stroke frequency and other swim related parameters. These algorithms have proven to be so accurate that it is no longer needed to install expensive underwater camera systems, but to wear one very simple to use Bluetooth swim sensor on the chest or back to get the same type of information. These algorithms can easily be translated in an even simpler device so that every swimmer can watch directly after their training in great detail their results. The Bluetooth swim sensor stores relevant swim parameters during swimming and sends them to your iphone or Android device using Bluetooth Smart / Low Energy. The Bluetooth swim sensor makes tracking your swim training fun, social and informative so that you can improve the quality of your training.