Nude swimming at my (all boys) school wasn't specifically prohibited but it wasn't compulsory either. I believe, looking back, that my naturism started at this period although I never quite realised what it was. After sessions in the gym or on the playing field (which I hated) we would be allowed to go for a quick dip in the school swimming pool and if you didn't happen to have remembered your swimming costume, it was no problem you could dip nude. I found this sensual and pleasurable although in the circumstances not erotic. I just liked nude swimming and on many occasions 'just happened' to forget my speedos when it wasn't too obvious. It once got remarked on by another boy who had spotted that I forgot my costume rather regularly. I haven't any recollection of what I replied on that occasion but as I say, looking back, I must have had a naturist inclination even then. Pity I didn't realise it and do more to develop my proclivity in earlier years. I might have become a much bolder and experienced naturist, found the appropriate community and able to enjoy it much more often today.
John