After visiting the famous beaches of Rio de Janeiro, where the skimpiest amount of cloth passes for a tanga (thong bathing suit) or the even minuter version called fio dental or dental floss, and beachgoers revel in exposing almost their entire bodies, it isn't surprising that Brazil is one of the few South American countries that have legalized nude or naturist beaches and resorts.
This is not without a struggle, though. The traditional and conservative attitudes toward nudity prevail in most countries of South America and have enforced set limits, even in Rio de Janeiro (though not successfully). Here's more on Brazil's nude beaches.
Brazilian naturism has its following and is rising in popularity with international nudists and naturalists. Several resorts, including Praia do Pinho in Balneário Camboriú, Santa Catarina state, and Colina do Sol cater to nudist and naturalist tourists specifically.
A word about going topless: Only in Brazil on designated beaches where women are allowed to go topless is this tolerated. Elsewhere, in all countries, it is not allowed, so go topless at your own risk.
No matter where you find a nude or clothing optional beach, there are certain courtesies to visiting a nude beach. And above all, if you're going to be exposing even more skin, don't forget your sunscreen!