Fitbit type thing for swimmer ?

[BeaLola]

Have a birthday coming up was thinking of a Fitbit perhaps - I would want one that I could swim in and would chart my lengths each week as well as walking distance. Any recommendations or indeed any to avoid ? Tia

I've not had a Fitbit but I do have the TomTom running watch which also does swimming. I like it but it's quite bulky.

I have flex2 which can be worn swimming but didn't record any swimming on holiday. You can manually add it though.