We could meet half way and shoot on the same spot simultaneously, but I'm not such a good swimmer....
But I'll use my 50 mm lens at f/5.6 on a sunny day with blue skies as well.
Just sent me a simple scan of your negative (or just a snapshot made with a d***l camera or phone) to show me your subject and I'll try to find a similar setting to shoot my film. It will be close enough for our empirical testing, I guess.
BTW: also let me know how you handled the salt. I'll do the same.