The Río Tinto is a highly toxic river in southwestern Spain that rises in the Sierra Morena mountains of Andalusia. It flows generally south-southwest, reaching the Gulf of Cádiz at Huelva. The Rio Tinto river has a unique red and orange colour derived from its chemical makeup that is extremely acidic and with very high levels of iron and heavy metals. The name rio tinto means "coloured river" in Spanish, in contrast to most rivers, which are clear. However, "tinto" is also an expression for red wine in Spain, so it is also related to this second meaning.