There is a place in the hills of south-east São Paulo state where you can hear a monkey you will probably never see. The muriqui, the largest primate in the Americas, lives in the Atlantic Forest of the Serra de Paranapiacaba, and Intervales State Park, one of the largest protected areas of that forest, is one of its refuges. The park covers more than forty thousand hectares of steep, misty hills, with giant ferns, bromeliads, orchids and trees hung with vines, and it is part of the Atlantic Forest South-East Reserves, listed by UNESCO in 1999. Toucans, tapirs and, rarely, jaguars share it.
Under the forest, the limestone has dissolved into caves, some of them open to visitors with a guide, with cool air, dripping water and formations. The park runs as an ecotourism area, with trails, birdwatching hides and simple lodging, so you can stay for a night or two. In the morning, mist rises from the trees, and the sound of birds is almost deafening.
Capão Bonito, a town of about thirty-seven thousand, is the gateway, with fuel, shops and restaurants, and it is the last reliable place to tank up. From there, the road to the park is a long one, with a stretch of unpaved track through farmland and forest, with red clay that turns into a slick, sticky mess in rain. Dry weather makes it a fine, dusty ride, but a heavy storm can close it, so ask at the town or the park office. The paved approach roads from Sorocaba and São Paulo are busy with trucks, with a lot of curves and fog on the higher parts.
The best season is the drier months, April to September, when the days are cool and the trails are firm. Summers are warm and wet, with sudden downpours. Bring layers, because mornings are cold, and insect repellent for the evenings. Try a plate of rice and beans with fried banana in a country restaurant, a strong coffee and a slice of corn cake, and give yourself time, because the forest does not hurry.