I spent an interesting hour in a Hong Kong
swimming pool a couple of decades when the high heat index stopped all hard physical training, we weren't complaining
. First watching a demonstration and then practising this. We were all quite surprised how effective it is even with thin cotton trousers which would last some time before needing a quick refill of air again.
The other thing that was demonstrated was entering water
without getting your face underwater. From an edge about the same level as the water, step forward and lean excessively forward with your arms out stretched. You glide across the water rather than dropping like a stone.
This stuff should be taught in schools really.