Between Ouro Preto and the neighbouring town of Mariana, this is the most ambitious mine visit in the area. A small open cable car descends 120 metres on a steep rail into the mountain, emerging in a flooded chamber where you can swim in the clear underground lake or row out in a small boat.
The mine operated from 1719 until 1985, producing more than 35 tonnes of gold across its life. The tour explains the brutal economics — life expectancy of an enslaved miner was around seven years — and the surviving 19th-century steam-powered equipment is impressive in its own right. Allow two hours, including travel from town.