What is the name of the river channel that connects the Amazon and Orinoco river systems?

The river channel that connects the Amazon and Orinoco river systems is the Casiquiare canal. Located in Venezuela, this natural distributary branches from the upper Orinoco and flows southward into the Rio Negro, which is a major tributary of the Amazon.

Unlike a man-made canal, the Casiquiare is a naturally formed river channel and one of the world’s most unusual examples of a bifurcation linking two major drainage systems. It is about 340 kilometres long and carries water from the Orinoco basin toward the Amazon basin. Its flow and size increase as tributaries join it along the route.

European accounts began with the Jesuit explorer Cristóbal Diatristán de Acuña in 1639, while Manuel Román travelled through the channel in 1744. The waterway’s existence was later verified by Spanish expeditions and explored by Alexander von Humboldt and Aimé Bonpland around 1800. A common mix-up is to call the channel the Rio Negro or Orinoco River; those are its connected waterways, not the connecting channel itself.