The Puelo River has its origin in a lake of the same name in Argentine

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 territory, and flows north-west through
the Andes

Andes

The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 into the Reloncaví Estuary

Reloncaví Estuary

Reloncaví Estuary is a fjord off Reloncaví Sound, located in Los Lagos Region of Chile. Several National Parks and Wilderness Areas are situated in the vicinity of this fjord. Among them are: Alerce Andino National Park, Hornopirén National Park, Vicente Pérez Rosales National Park, Llanquihue...

 of the Reloncaví Sound

Reloncaví Sound

Reloncaví Sound or Seno de Reloncaví is a body of water located immediately south of Puerto Montt, Chile. It is the place where the Intermediate Depression falls into the Pacific Ocean. There are several islands in the sound including Tenglo Island, Maillén Island and Huar Island...

 at the northern end of the Gulf of Ancud

Gulf of Ancud

Gulf of Ancud is a large body of water separating the Chiloé Island from the mainland of Chile. It is located at .-External links:*...

. Its lower course is impeded in such a manner as to form the Lake Tagua Tagua. A large northern tributary of the Puelo, the Manso

Manso River (Argentina)

-References:* Rand McNally, The New International Atlas, 1993.*...

, has its sources in Lake Mascardi and
other lakes and streams south-east of the Cerro Tronador

Tronador

Tronador is an extinct stratovolcano in the southern Andes, located along the border between Argentina and Chile near the city of Bariloche. The mountain was named Tronador by locals in reference to the sound of falling seracs...

, also in
Argentina, and flows south-west through the Andes to unite
with the Puelo a few miles west of the 72nd meridian

72nd meridian west

The meridian 72° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, North America, the Atlantic Ocean, the Caribbean Sea, South America, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole....

.