You need to tell her that going topless outside, even on the back deck, is not acceptable in most social settings. It could attract unwanted attention or cause problems with neighbors. Maybe suggest some more private areas in your property where she can be more relaxed without being inappropriate.
First, you should quickly cover her up to avoid any inappropriate exposure. Then, have a serious conversation with her about appropriate behavior in public or semi - public areas. It's important to respect the privacy and social norms.
In most cases, it's not acceptable as it goes against social norms and can be considered inappropriate, especially if there are neighbors or the possibility of others seeing.
In many places, it depends on the level of privacy of the back deck. If it's completely secluded and not visible to the public, it may be within the realm of legality. But if there's any chance of being seen by neighbors or passers - by, it could potentially violate public decency laws.
It depends on the location and the cultural norms. In some private and secluded areas where it's allowed and not offensive to others, it might be okay. But in public or more conservative settings, it would likely be considered inappropriate.
It is not appropriate behavior in most public areas of a hotel. Hotels are public places with certain standards of decorum. Going topless violates the general norms of public modesty and can make other guests uncomfortable.
Acceptability is a subjective matter. In cultures where topless beaches are common, like in some parts of Europe, it may be seen as normal. Your wife's choice to go to a topless beach could be a statement of self - confidence and body acceptance. She may be embracing her body as it is and enjoying the freedom that such a beach offers. However, it's important to be aware of the potential reactions from others, but ultimately, if she is comfortable and not violating any rules, it can be a positive experience for her.
You should first consider the location. If it's a private place, you can let her do it if you both are comfortable with it. But if it's not, you should gently explain to her the potential issues.
Going topless in a cruise balcony is not okay. Cruise ships are public spaces in a sense, even the balconies as they can be overlooked. There are norms of propriety to follow, and being topless goes against those. It can also make other passengers uncomfortable. Moreover, different regions and cultures have different views on what is acceptable in public, and cruise ships usually operate in multiple regions with diverse cultural expectations.
If this is just a story for shock value, it's not something that should be encouraged. We should abide by proper dress codes and social norms, especially in public areas like on a boat where there are likely to be other people around.