Halfway between Rio and São Paulo, Ondine Cohane discovers hidden beaches, colonial villages, and palmy, pristine deserted islands. Style Director Mark Connolly packs easy-elegant togs to charm the region's new nexus of jet set and intelligentsia

Ten days before Carnaval, Rio is shifting into overdrive, preparing for the hot-blooded crowds while samba schools practice late into the night for their moment in the spotlight. But from where I'm sitting, only a hundred miles to the southwest, it's hard to imagine that such a bacchanal is taking place—or even that such a teeming metropolis is just a two-hour drive away. Here on Brazil's Costa Verde, the spectacle is the Mata rain forest, small fishing towns, and the jade-green Atlantic. (Once, the rain forest stretched the length of the entire coast, over a thousand miles, to Bahia.) Empty sawtooth bays are backed by forested mountains. On the waterfront, fishing boats head out to sea, while a few white-sailed sloops do day-trips to nearby islands. It's no wonder these hidden beaches, deserted islets, tiny villages, and colonial towns between Rio and São Paulo are becoming favored retreats for well-heeled Brazilians and jet-setters who arrive by speedboat or helicopter.

I start my tour of the 365-island archipelago of Angra dos Reis ("Bay of Kings") on its largest landmass, Ilha Grande, a 119-square-mile tropical island that was first home to coffee plantations and then to a penal colony (until it became too expensive to transport prisoners and food across the bay). As I make my way around the 106 white-sand beaches and blue lagoons whose sandy bottoms are littered with yellow and orange starfish, I can't help but be relieved that tourism came here only in 1994—and in such a gentle form. The jungle seems to want to reclaim whatever has been built on its shores, creeping down as far as it possibly can without touching the saltwater. There are no cars on the island, and the only way to explore the rain forest is on foot, with the most challenging hike being the one to the top of 3,200-foot Pico do Papagaio ("Parrot's Peak"). Rio's stylish set are not inclined to make the effort, preferring to hop on a boat and retreat to a cove to sunbathe and sip caipirinhas.

I have a boat of my own and am in the care of Hernani, a former fisherman, and Robson, a guide for Blue Parallel Expeditions. We stop at the island's main town, Vila do Abraão, a small stretch of restaurants, posadas, and a couple of trinket shops along the beach. Like most of the tiny villages around here, it has a whitewashed church surrounded by flowering trees. From Playa de Palmas, it's a twenty-minute walk to Lopes Mendes, Ilha Grande's most famous beach: Its position on the open Atlantic makes it impossible for smaller boats to reach the shore. I am still recovering from a broken ankle, and after attempting the steep rocky trail, I realize that I will have to sit this one out. I send my friend Barbara to investigate with Robson and lounge under a tree, listening to the samba beats from the anchored boats. After an hour, Robson and Barbara return, and I try to sound curious rather than jealous at their reports of a wide expanse of soft white sand and clear water, not to mention the tanned Brazilians surfing the big waves. But my envy is soon forgotten when we get dropped off at the Pestana Angra, a bungalow property tucked into the vegetation at the water's edge. I take note of the beach pavilions with mattresses big enough for two—perfect for a quiet hour—and the open-air spa.