The sensor was fine through the first night. I was delighted to see the graph of the night's blood sugars. (I'm easy to please!!)
Got to the pool for 8:30, but unable to use sensor for pre-swim blood sugar check, as the reader was already in need of recharging!
However, though unable to read the sensor, the sensor stayed on my arm throughout a 30 minute swim. I stuck to the rules outlined in the handbook and mentioned above by
@Brunneria :
'Your Sensor is water-resistant and can be worn while bathing, showering or swimming. Do NOT take your Sensor deeper than 1 metre (3 feet) or immerse it longer than 30 minutes in water.'
The sensor stayed on ok throughout the swim plus showering, shampooing, drying, dressing, staggering to Nero's for first coffee of the day. There I resorted to finger stick bloods as my Libre reader was uncharged.
To be honest, it was a success, the worst aspect being nervous about wearing something relatively expensive (not a diamond tiara I know) in a swimming-pool. I would prefer to wear some sort of cover over the sensor, but haven't yet sussed what I could use. I will try
@Brunneria 's suggestion of Opsite, and maybe look for something like a neoprene arm band.