The plain lying between this coast range and the Andes dips below sea-level in the gulfs of Ancud and Corcovado (average width, 30 m.).
The culminating point of that part of the Carioca range which projects into and partly divides the city is the Corcovado (Hunchback), a sharp rocky peak 2329 ft.
Railway communication with the interior is maintained by the Central do Brazil (formerly the Dom Pedro II.), Leopoldina and Melhoramentos lines, besides which there is a short passenger line up to the Corcovado about 21 m.
These archipelagoes are separated from the mainland in the north by the gulfs of Chacao (or Ancud) and Corcovado, 30 to 35 m.
Inside the island of Chiloe the large gulfs of Chacao (or Ancud) and Corcovado are well protected from the severe westerly storms of these latitudes, but they are little used because the approach through the Chacao channel is tortuous and only 2 to 3 m.
It receives one large tributary from the south, the Rio Pico, and enters an estuary of the Gulf of Corcovado a little north of the 44th parallel.