The Big Island of Chiloé is the second largest in South America after Tierra del Fuego. It is separated from the continent by the Chacao canal and from the Andean mountain chain by an interior sea which extends more than 100 miles to the south. The western side of the Big Island presents an abrupt and inhospitable coastline, with the eroded relief of the thousand-year-old coastal mountain range.
This mountain chain, no higher than 1,000 meters, is abruptly cut by two lakes, the Cucao and the Huillinco and despite rising again further to the south, does not maintain its backbone intact. It changes name to the Piuchue range in its northern section and the Pirulil to the south. Apart from these headlands covered with impenetrable forest, the outline of the Big Island is more gentle than rugged.
The Big Island of Chiloé is separated from the continent by an interior sea, divided into strips by transversal groups of islands ranging from east to west. This inland sea is formed by the Reloncavi sound, the golf of Ancud and the golf of Corcovado.
While the western side of the island confronts the fearsome Pacific Ocean, the eastern side unfolds in gentle hills that turn into fields, meadows and scrubland which reach to the canals of the interior sea. The length of this interior littoral is clothed in an exuberant landscape of green ferns, brush, scrublands and thickets, with dozens of coves and creeks.
The climate on the Chiloé archipelago is temperate, maritime and rainy, with average temperatures of 10º C. There is precipitation all year round but the rainiest months are between May and August, when almost half the annual total falls.