I will be going swimming tomorow in a bathing suit. My friend in a bikini. I will not judge her for it, she can wear what she wants. I for one am wearing a swimming costume to be more covered than if in a bikini. However, I could be more modest and weqr the skirt version. However, if I did some guy might find that interesting too.
I could just not go swimming but it is my daughter's birthday and am taking her because kids love swimming. I go on Tuesdays for toddler's lessons and on a Thursday to exercise. I do not feel immodest in a costume, thankfully. I have never noticed anyone particularly looking. But I'm not interested if anyone is looking anyway, my intent is the activity. One time I saw someone from my old church and he went to hug me. I had to refuse the hug, which was a surprise to him that I didn't think it proper. He didn't ask for explanation but I saw him work it out. I conclude that the guy was there for swimming rather than looking at women, so the thought of modesty hadn't entered his head. I was still just a sister in Christ; not an object to be appreciated but a person to be respected. It might have been right for him to hug me but it wasn't right for me to hug in that attire.
I would think on the beach that it is the intent behind the bikini which matters. I, for one, will not buy my daughter a bikini because I see them as wrong on a child. A child has no breasts so I think it is inappropriate to put one on. I remember as a child just wearing knickers on the beach if I didn't have my costume.
Other women they can decide for themselves what to wear. A christian women ought to carefully evaluate her choice.
A christian man ought to control himself and allow her to have her own choice; without blaming her for his own folly. If we do not take full responsibility for our own actions we can not have real integrity, or repentance.
Also, a Christian man visiting the beach should know his own mind. Surely walking in the Spirit helps in this scenario. If he can't control himself he should probably avoid going to the beach.
Matthew 5:29