The Rio Santo Antônio in Minas Gerais is a tributary of the Rio Doce, rising in the Espinhaço Mountains near the district of Santo Antônio do Cruzeiro in the municipality of Conceição do Mato Dentro. From its headwaters it runs generally eastward for approximately 287 kilometers before emptying into the Rio Doce.

The river is characterized by a rocky course punctuated by a number of waterfalls, which define much of its paddling character. Among the most notable is Tabuleiro Falls, recognized in the 2005 edition of the Guia 4 Rodas as the most beautiful waterfall in Brazil. The presence of multiple falls along the course means paddlers should expect significant portages and should scout carefully before committing to any rapid or drop. The rocky, technical nature of the river makes it a more demanding waterway rather than a casual flatwater paddle.

Historically, the river served as a transportation corridor for bandeirantes during Brazil's Gold Rush era. Today it sees use for fishing, gold panning, and leisure and tourism activities.

Given the river's length and the presence of waterfalls, any multi-day trip would require thorough advance planning, including portage logistics around the falls. Paddlers considering this river should seek current local knowledge regarding access points, water levels, and the precise locations and severity of the waterfalls along the route.