Wa Alaikum Assalam and thank you for your question.

Muslim scholars will tell us what is lawful and what is unlawful. So if a man at the beach is wearing a swimming suit that covers him from his navel to his knees then Muslim scholars will say that it is lawful (halal).

Their answer is not location based, beach or not, it is based on the definition of men’s awrah (what shouldn’t be exposed from the body).

It is possible for some Muslim scholars to issue a fatwa saying that it is unlawful for men to remove their shirts when not on a beach. However, some others might see it too restrictive because some men might need to remove their shirts to do their work, for example.

In general, this is not a problem that arises among the Muslims so you might never see such a fatwa.

Obviously no sane Muslim would go out in public not a beach without his shirt on because it is not appropriate; we don’t have to be told it is halal or haram.

Culturally speaking, men who do so are not respectful people. You sometimes sense arrogance or ill-manners from the way they behave.

Non-Muslims do not have any laws to follow except man-made laws. Since it is not forbidden by state law that a man may walk without a shirt then they are not breaking any law.

I hope this helps answer your question.

Salam and please keep in touch.