Martin Parr is a self-proclaimed "aficionado of the British seaside". Since his controversial project of 1985, The Last Resort: Photographs of New Brighton, in which the documentary photographer captured the highs and lows experienced by residents and day-trippers at a run-down resort on the Wirral Peninsula, Parr has braved the wind-beaten shores of beaches across the country. For his latest project, Playas, the 57-year-old and his wife Susie went a little further afield. The couple spent several years visiting some of the biggest resorts in South America, travelling between Brazil, Uruguay, Mexico, Argentina and Chile in the process. Be it home or abroad, Parr explains, there is something endlessly appealing about the beach.

"The seaside has to be one of the most fascinating places for people-watching," he says. "It is a place where we relax and lose our inhibitions, and that's when true personalities come on display." The fact that revellers of all shapes and sizes are physically exposed, in various states of undress, means that they enjoy a shared sense of community as they meet people who they wouldn't otherwise encounter in their everyday life – "that in itself is revitalising," says Parr. The photographer views the beach as a microcosm of society which allows us to observe the habits and tendencies belonging to particular cultures. "If you're in Mar del Plata, Argentina's largest resort, for example," says Parr, "you are very likely to be drinking 'mate', a local green tea. Elsewhere in South America, beer and cola is more common. Another telling little difference is that, in Mexico's Acapulco, you'll find that people wear lots of clothes at the beach, which reflects the more reserved character of the locals". Compare this to Salvador's Barra beach – where people hardly wear anything.

Parr was particularly taken with Mar del Plata, "Argentina's answer to Blackpool," he says. "It's very big, very busy and slightly polluted. It's rather like how Coney Island was in the 1960s, too: a little bit dirty and therefore one of the best in the world to photograph."

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'Parr's Playas', £17, chrisboot.com