The Guardian has this slideshow on the country’s top 10 beaches.
But the Huffington Post has a feature on the world’s most dangerous beaches and includes both Rio’s Copacabana and Boa Viagem in Recife on their list. The former because of crime and the latter because of the danger from sharks.
I like Trinidade from the Guardian pick (pictured above) but when I lived in Rio the beach I most liked to go to was Prainha. More for the view from the no frills restaurant overlooking the horseshoe bay than the beach itself. You could sit up there eating fried fish and watching the surfers. Lovely….