The eight largest islands are from northwest to southeast: Gran Guaiteca, Ascención, Betecoy, Clotilde, Leucayec, Elvira, Sánchez and Mulchey.

[1] The islands have subdued topography compared to the Andes, with Gran Guaiteca containing the archipelago's high point at 369 m (1,211 ft).

In the second half of the 19th century, the islands became permanently settled as consequence of a wood logging boom centered on Ciprés de las Guaitecas (Pilgerodendron uviferum), a tree named after the archipelago.

[4] From September to December high tides in combination with storms produce large waves that wash over land depositing sand and gravel onshore.

[5] The main vegetation assemblage of the islands is the Bosque Siempreverde con Turberas de los Chonos (lit.

[4] Other trees in these forests are Nothofagus nitida (coigüe de Chiloé), Metrosideros stipularis (tepú) and Weinmannia trichosperma (tineo).

[6] In the ground of the more-less open Pilgerodendron forest cushion plants such as Astelia pumila, Donatia fascicularis and Oreobolus obtusangulus grow.

[7] In the western fringes of the archipelago the vegetation is made up of a c. 2-meter (6.6 ft) high shrubland of Pilgerondendron and Nothofagus nitida.

[10][11] The Gulf of Corcovado to the north of the archipelago is "arguably the largest feeding and nursing ground for blue whales [...] in the entire Southern Hemisphere".

[20] The islands made up the southern limit of Pre-Hispanic agriculture[21] as noted by the mention of the cultivation of potatoes by a Spanish expedition in 1557.

[D] These explorations were driven by religious motives in the case of Jesuits and by rumours about settlements made by rival colonial powers as well the search for the mythical City of the Caesars.

[24] Jesuit Mateo Esteban who visited the islands in the 17th century estimated its population at 170 individuals, 120 of which he managed to gather in a meeting.

[26] As result of a corsair and pirate menace, Spanish authorities ordered the depopulation of the archipelago to deprive enemies of eventual support from native populations.

[23] Following the decline of the Chono populations in the archipelago in the 18th century, the area gained a reputation of "emptyness" among Chileans akin to the description of eastern Patagonia as a "desert.

[31][29] Felipe Westhoff, a German-Lithuanian immigrant who operated a Pilgerodendron uviferum logging business from Ancud, founded Melinka in 1860.

[34] When Westhoff's time spent in the archipelago diminished in the early 1870s the title of subdelegado marítimo passed to his associate Enrique Lagrèze.

[4][29][37] Álvarez business owned him the nickname of "The King of Pilgerodendron" (Spanish: El Rey del Ciprés)[35] and had great effects on the incipient economic development that came to link the archipelagoes of Chiloé, Guaitecas and Chonos.

[38] Felipe Westhoff wrote:[38][20] One of the most famous of the early outlaws was Pedro Ñancúpel a pirate who was captured in Melinka in 1886 and bought into justice in Ancud the same year.