The sleeper hit of the Cyclades, Serifos is the summer retreat of interior designers and architects who prefer to keep the sandy beaches to themselves. (One French home-owner is so protective of her hideaway that she tells all her friends she summers on nearby Sifnos.) Even in August, you’ll find coves where you can skinny dip in blissful solitude. That’s because the best beaches (Kalo Ambeli, Vagia, Skala) are only accessible via bone-rattling dirt roads or donkey tracks. Better still, rent a motor boat from the laidback harbour, Livada.