Caverna do Diabo State Park, Protected cave system in Eldorado, Brazil

Caverna do Diabo State Park covers 40,174.82 hectares across Barra do Turvo, Cajati, Eldorado and Iporanga, protecting dense Atlantic Forest with a 25-metre canopy and araucaria stands. Its main cave, Caverna da Tapagem or Caverna do Diabo, follows an underground stretch of the Rio das Ostras in the Serra de André Lopes and is over 5 kilometres long, with 600 metres fitted with walkways and lighting.

The cave was discovered in 1896 by Ricardo Krone, who mapped the underground passages by following the Rio das Ostras river. This discovery led to recognition of the site's importance as a natural and geological treasure.

Local quilombo communities live within the park region, maintaining settlements that date back to the period when enslaved people found refuge in these forests. Their presence shapes how the landscape is used and respected today.

The cave entrance is at Km 111 of the SP-165 highway, at the Caverna do Diabo Center in Eldorado, where the park base has a visitor center, restaurant and parking. Visitors pay an entrance fee plus a separate fee for the environmental monitor who must accompany them. Of the cave's roughly 6,000 metres, only 600 metres are open, fitted with walkways and lighting. Two trails leave from the base: Araçá and Mirador do Governador.

The cave follows an underground stretch of the Rio das Ostras in the Serra de André Lopes and is over 5 kilometres long, yet only about 600 metres are open to visitors. The rest of the passages, beyond the lit walkways, are not part of the regular tour.