The Orinoco River, also known as Rio Orinoco in Spanish, has been referred to by various synonyms. One of the most common synonyms is "Orinoco Delta," which refers to the river's vast estuary where it meets the Atlantic Ocean. Another synonym is "Rio Negro," which comes from the river's dark waters. The Orinoco River is also sometimes called the "Amazon of Venezuela" due to its ecological richness and biodiversity, similar to the Amazon Rainforest. "Rio Apure" is another synonym for the Orinoco River as it is the largest tributary in the Orinoco Basin. Lastly, indigenous people of the area have referred to the river as "Cuao," which means "great serpent".