Head down a dusty track along Herdade da Comporta, an expanse of coastline just an hour from busy Lisbon, and you could find any number of surprises. You will see solitary majestic villas - one reason why this stretch of sand in the rural Alentejo region has been compared to the Hamptons of the 1970s - or, like me, a sapphire-coloured expanse of lake with dragonflies dancing across its surface. This idyllic 60km enclave of golden beaches, forests, salt marshes, rice fields and seven small hamlets is Portugal's best-kept secret - so much so, it's where celebrities come to escape the paparazzi and play.
The Hollywood and fashion A-listers spotted on these sands include Harrison Ford, Kristin Scott Thomas, Christian Louboutin and Mario Testino. French power couple, former president Nicolas Sarkozy and Carla Bruni, holiday here, and Princess Caroline of Monaco and daughter Charlotte Casiraghi can be spotted, dressed down in kaftans and flip-flops, on their annual visit every July.
Discover the area on a chilled-out bike ride or visit Cavalos Na Areia stables to rent a horse ride across the rice fields and dunes to the beach. Gently clopping through sand and surf on a horse is an incredible way to experience cool Comporta close up.
Pass umbrella pine trees polka-dotting the landscape, storks nesting on the chimneys of traditional thatched houses and flamingos hiding behind sand dunes. Only the occasional shack-life restaurant crops up, thanks to the area's protected status keeping development to a minimum. For a Speedier getaway, hire a Mini Moke beach buggy and whiz to one of most-visit beach restaurants for lunch.
Restaurante Sal is the place to see and be seen - try the fish soup and black rice with cuttlefish - while O Dinis Bar in Carvalhal, owned by a fisherman, serves great seafood. Platters of clams with garlic, fat pink prawns and choco frito (cuttlefish in batter) arrive, followed by a huge fresh sea bass, expertly filleted by the waiter while you watch.
Afterwards, head to the boutiques of Comporta village and browse designer swimwear and jewellery. Begin the night here, with cocktails and Balearic beats at Colmo bar, followed by more great food at Museu Do Arroz. This much-touted restaurant within a former rice-husking mill stays open late when the crowd is buzzing.
Stay at the renovated Sublime Comporta, to experience a different kind of bliss. This stylish country house retreat, which added a new restaurant and ten family villas as part of the renovation, is also home to a spa, 14 rooms and guest suites, plus a selection of two, three and, soon, five-bedroom villas each with its own private pool.
With the sun shining long into autumn, there's still time to enjoy Comporta - just keep it under your sun hat. We don't want everyone knowing.