And the answer: the Amazon River.
Due to a lack of interest and no available roads, no bridges cross the Amazon River. A bridge along the 4,300-mile-long river would require extensive engineering and construction and might induce deforestation. There is, however, one bridge along the Amazon’s main tributary at Rio Negro in Brazil, which connects the towns of Manaus and Iranduba.
The Amazon is one of the most famed and culturally significant rivers in the world. Its massive water output fuels the lush, tropical climate of the Amazon rainforest, while its shores supply water to countless communities and wildlife species. However, did you know that the Amazon actually used to flow in the opposite direction? Between 65 and 145 million years ago, the Amazon River flowed towards the Pacific Ocean— the opposite direction it flows today. Over time, the rise of the Andes mountains forced the river to reverse its course.
The Amazon is also the world’s largest river by volume. The freshwater outputs of the Amazon clock in at around 200,000 liters every second. Impressively, the Amazon accounts for over 20% of all freshwater that enters the ocean. As such, it’s only natural that the Amazon has a significant impact on the oceans it flows into. In fact, the Amazon releases so much water into the Atlantic ocean that it actually alters the sea level of the Caribbean sea! This is due to the Caribbean current, which carries the water to the Caribbean islands and raises the water level around 3 centimeters.
There is a unique species of dolphin which lives only in the Amazon river! Also known as the pink river dolphin or boto, the Amazon river dolphin is one of just four species of "true" river dolphins. Scientists believe that this specific species of dolphin evolved around 18 million years ago.
Learn more about the Amazon river here.