The Rio Quebó Grande is a river located in the municipality of Nobres, Mato Grosso, Brazil. It is known for its exceptionally clear, pristine waters and is a focal point for adventure tourism in the region. A highly recommended and popular route for paddlers and floaters is a 1.9-kilometer (approximately 1,900-meter) descent along the river. This route includes a notable 278-meter passage through the Duto do Quebó cave, which involves floating through the cavern. The total descent for this specific activity is often cited as 2 kilometers. The experience is characterized as a fun and adventurous float trip, with the river offering stunning landscapes. The area surrounding the Rio Quebó Grande is noted for its preserved natural environment. The river is part of a broader circuit that can include other local features such as the Lagoa dos Jacarés and the Olho d'Água reserve. The primary access for the Duto do Quebó tour is located approximately 51 kilometers from the town of Nobres. The activity, often referred to as Boia Cross, involves floating with the aid of life vests and provides opportunities for snorkeling in the transparent waters. There is no information indicating any restrictions on paddling, but the described tours are clearly structured commercial adventures.