Fortaleza Canyon, Natural canyon in Serra Geral National Park, Brazil.

Fortaleza Canyon is a canyon in Serra Geral National Park, on the border of Cambará do Sul, Rio Grande do Sul, and Jacinto Machado, Santa Catarina. Its vertical walls of pale grey and tan volcanic rock rise from the valley floor, streaked with dark bands and split by deep fissures. Green vegetation covers the plateau above the cliffs and grows along the ledges, and a tall, thin white waterfall drops down the rock face on the right.

The canyon formed through volcanic activity and erosion working over millions of years. These geological processes shaped the region and created the landscape of southern Brazil.

The name Fortaleza means "fortress" in Portuguese, and the canyon marks the state line between Rio Grande do Sul and Santa Catarina: the plateau rim lies in Rio Grande do Sul, while the cliffs and valley floor belong to Santa Catarina. The Fortaleza sector has its own trails, Borda do Fortaleza, Mirante and Pedra do Segredo, open until 15:00, or 21:00 during daylight saving time.

Access is via two main hiking trails, each taking about two hours and offering different perspectives of the canyon. Sturdy footwear is essential since the paths are rocky and sometimes steep.

Fortaleza Canyon lies on the state line: the plateau rim is in Rio Grande do Sul, while the cliffs and valley floor belong to Santa Catarina. The canyon separates the municipalities of Cambará do Sul and Jacinto Machado. Its cliffs are part of the Serra Geral Group, volcanic rock of the Paraná-Etendeka Province, and erosion there runs at only 6 to 50 metres per million years.