I've long thought this looks like a good way to be on the water. Haven't tried it, though; we live on the coast and the sea is usually with too many waves and wind to make it easy to stand up when you're a beginner... maybe we just need to go find a lake, instead.
Looks very refreshing; could have use something like that when we recently had a week of 35+C here, which is very unusual!
Yes, lakes and slow rivers are fine for SUP, but could be not so easy in a sea, on a windy day especially