Mato Grosso, located on the edge of the Amazon is mostly populated on the south. Capital city is Cuiabá. I have heard that Cuiabá is a beautiful city and has some hot springs. There is frequent air service from São Paulo.

The big attraction of Mato Grosso and also Mato Grosso do Sul is the national park "Pantanal Mato Grossense." From what I have learned is this area is not just swamp land, but huge wildlife reserve. It is estimated to have the largest bird population in the world. Here are some links so you can learn more.