There are a number of nude and/or naturist beaches and clubs in Central America and the Caribbean, but to date, relatively few in South America.
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 beach goers 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.
Not without a struggle, though. The traditional and conservative attitudes toward nudity prevail in most countries of South America, and try to set limits, even in Rio de Janeiro... but not successfully. Here's more on Brazil's nude beaches.
Brazilian Naturism has its following and is rising in popularity with internationsl nudists and naturalists who take note of various resorts, including Praia do Pinho in Balneário Camboriú, Santa Catarina state, and Colina do Sol for a preview of the resort before visiting.
A word about 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. 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.
Don't forget your sunscreen!