What south American river flows through Venezuela and has a name starting with O?

The Orinoco River is a major river in South America. It flows through Venezuela and Colombia and has a length of 2,140 kilometres (1,330 miles). The Orinoco River is the fourth longest river in South America and the largest river by volume of water discharge in South America. The Orinoco River is also one of the most biodiverse rivers in the world.