Many cultures that expect some level of modesty associate nudity with sexuality. These cultures usually know striptease in some form. When the difference between the sexes is shown in the main stream media of these cultures this is often seen as sexually related. In Latin cultures the common definition of modesty does not generally allow genital nudity, but the definition of what is lewd has changed and women's breasts are now commonly exposed or depicted without scandal.
Nudity in front of a sexual partner is widely accepted, but there may be restrictions—for example, only at the time and place of sex, or with subdued lighting, during bathing with the partner or afterwards, covered by a sheet or blanket, or while sleeping.
In Ancient Greece it was seen as normal that the athletes taking part in sporting events, like the Olympic Games were nude, for most events. At that time, women were not allowed to take part or in the games or watch them. Nudity with women was frowned upon.
In the 20th century, it was very common for boys to swim nude in the United States. Boys usually found rivers, ponds or lakes to swim in. If there were no girls or adults there, boys just took off their clothes to go swimming. In the United States, recreational (fun) nude swimming (but not school nude swimming) is often called skinny dipping. Boys didn't care if other boys saw them without clothing. Poor boys and farm boys did not even own a bathing suit. Some teenagers, usually boys, still go skinny dipping. It is most common outside of cities.
Until the mid-1960s boys were usually nude in swimming pools. From the 1890s until 1962, men and boys used to swim nude at the YMCA (Young Men's Christian Association.) The YMCA is an organization with many swimming pools in the United States. After women were allowed to join the YMCA, the rule changed. Nobody could swim nude there.
At school swimming pools and public swimming pools there were different hours for boys and girls to swim. Sometimes the pool had bathing suits for girls to wear. Many families did not have money to buy bathing suits for children then.
Teachers told boys to swim without a bathing suit at most high schools in the United States. It was normal for boys. Swimming nude at school was usually not allowed for girls. (A few schools had nude swimming for girls. At some schools, girls were not allowed to swim at all.) The boys had to swim nude in high schools in Houston, Texas from 1930 or earlier until the mid-1960s. In Chicago, Illinois schools, boys were required to swim nude until in the early 1970s.
Until the 1960s, nude swimming was the rule for men at many colleges and universities. Some colleges had only male students. Other colleges had only female students. At colleges with men and women, there were separate pools or different swimming times for men and women.
In the United States and Canada, there is not nude swimming at school now.
There are some places where people swim nude. People swim nude at special clothing optional beaches. Usually these are called nude beaches. It is not as common in the United States and Canada as in Europe. Sometimes a city or county owns the beach. Sometimes a state or province owns the beach. Sometimes the federal (national) government owns the beach. Optional means people can swim nude or with a bathing suit. Usually the government does not tell people they must be nude. Each person can choose what to wear.
Some people have a pool in their house. Some people have an outdoor pool or a pond in their backyard. Some people swim nude in their own pool or pond. Sometimes neighbors complain. Some people swim nude in lakes or rivers when they go camping. Some public pools have special hours or special days for nude swimming. That is more common in indoor public pools.
Clubs for people who like to be nude usually have nude swimming. These are usually called naturist clubs or naturist retreats. A retreat is like a camp or park. It is usually away from the city. Many years ago they were usually called nudist clubs. The name nudist club is less common now. If there is enough space, the club may have other nude sports. They sometimes have nude volleyball or nude basketball. They sometimes have nude soccer (football) if they have a big space. Sometimes people use boats without clothes. People sometimes use a sailboat, rowboat or canoe nude. Sometimes a camp or retreat owned by a church has nude swimming or other sports.
If there is a swimming pool or pond at a house, sometimes teenagers are happy to swim nude with their teenaged friends or with their brothers or sisters. They might not want to be seen nude by their parents. They might not want to be seen nude by much younger brothers or sisters. Sometimes parents are happy to swim nude with other adults. They might be happy to swim nude with young children. But they might not want to be seen nude by teenagers.
Sometimes people have different rules (sometimes called social norms) at different places. For example, people in a family might not be naked at home. They might always put a towel around themselves after a shower or bath. But if they go somewhere else, the rules might change. Families sometimes go camping or to a cabin (also called a lake house or beach house or cottage in some places) for a vacation (holiday). The people in that family might swim or lie in the sun nude there. They might eat breakfast together nude. Same people. Different place. What is normal, expected, or comfortable for them changes with the place or situation.
Some families with an outdoor swimming pool at their house have a no nudity inside the house rule. They swim nude, lie in the sun nude, but they put clothes or a towel on when they come inside the house. The rule may be to show politeness or respect for others. A fancy expression for this is a matter of decorum. It is comparable to a rule like "mobile devices (like phones) can be used at breakfast but not at the evening meal."
At least since the early 20th century there is a movement of people wanting to do some things together, while they were nude. Sometimes it was just seen functionally, like a common bath in a pond or lake. Some people do other activities together (in the nude), where being naked is usually not required. For instance, some people prefer nude sunbathing when otherwise a swimsuit could be worn. There are some nude bicycle tours. This movement is generally known as naturism or nudism. In 2009, Appenzell Innerrhoden, a small Swiss canton, voted to stop nude hiking. German tourists have been walking nude through the Alps wearing only boots, socks, and a back pack. The canton will fine nude hikers 200 Swiss francs.
The Naturism movement of the 20th century claims that being nude is healthy. Starting in 1853, reformer Arnold Rikli said that "Sun- and air-bathing" is a good thing, and that it can only give its full potential when done in the nude. Many of these views have been proved wrong today. Not smoking or drinking alcohol is good for health, regardless of whether clothing is worn or not. People suffering from being exposed too little to the sun will also be so if they are clothed. Wearing wet clothes can lead to cystitis (an infection of the urinary bladder).
Some doctors recommend sleeping in comfortable clothes, or sleeping naked. At some points in time, fashion dictates very tight-fitting clothes. These can be bad for health.