Capitólio is a small town in southwestern Minas Gerais, on the shore of the Furnas reservoir — the 'sea of Minas', a huge artificial lake created by a dam in the 1960s. Where the water flooded the valleys it left dramatic canyons of layered rock, and boat trips into these, with waterfalls pouring in from above, are what bring people here.
The classic trip is through the Cânion de Furnas and the Paredões, where boats nose up to waterfalls between sheer walls. On land, the Cachoeira do Poço Dourado and the waterfalls of the Serra da Canastra foothills are a short drive away, and the Mirante dos Canyons gives the view down over the lake.
In January 2022 a slab of rock collapsed from a canyon wall onto tourist boats, killing ten people. Access to the canyons has since been reorganised, with safety rules and exclusion zones, especially in the rainy season; check the current situation before you book, and go with an authorised operator.