@Happyyooper the vibration feature is one of the most useful on my G. watch when I swim. Not only every 100m but I can set it up to vibrate every n-lengths. If I do 500m intervals, I set it to vibrate halfway so it reduces the need for counting (1st vibration, 250m, 2nd vibration - done). There were several topics here about swim tracking and Sense 2 (I went back to the original Sense which shows more details yet it doesn't have vibration, which Fitbit watch vibrated on 100m?) and it's probably the worst possible (next to having no tracking) option for swimmers. I can't imagine counting laps in my head when I have a watch to do so for me. There is no drill tracking (some drills may not trigger laps like leg drills), and no rest state (so that you'll get only moving pace, there is a big difference in elapsed pace and moving pace). AZM is granted out of nothing (no HR is used during swimming). I assume intensity takes into account stroke rate (which should be a metric but Fitbit doesn't know about it), stroke style and duration between laps (to measure distance) but Fitbit is so bad at detecting the style that calories and AZMs will be off (and why AZM without HR at all?). If you need swim tracking you may get a dedicated watch and log swimming into Fitbit manually based on different devices tracked.