Do most South American rivers flow into the Pacific or Atlantic Oceans?

Most major South American rivers flow into the Atlantic Ocean. The Amazon River, the world's second longest and largest river, flows through much of the continent and empties into the Atlantic Ocean near the city of Belém, Brazil. Other major rivers that flow into the Atlantic include the Paraná River, which forms the border between Brazil, Paraguay, and Argentina; the Uruguay River, which flows between Uruguay and Argentina; and the São Francisco River, which is located entirely within Brazil.

By comparison, relatively few major South American rivers flow into the Pacific Ocean. The largest of these is the Magdalena River, which flows through Colombia before emptying into the Caribbean Sea, which itself is connected to the Atlantic Ocean. Other notable rivers that flow into the Pacific include the Biobío River in Chile, the Guayas River in Ecuador, and the Rimac River in Peru.