I have been looking for swim trackers for a while. I tried the swim.com app on the original Pebble smartwatch - it worked sometimes, but often missed laps. I tried the swim.com app again on the Sony Smartwatch 3 (the only waterproof Android wear device at the moment) and it failed to synchronise the swim data every time.
Earlier this week I bought the new Misfit Speedo Shine device. After three days of trying it out, I can say that this device is perfect.