Chiloé Island is separated from the Chilean mainland by the Chacao Channel in the north. Most of the good harbors are located on the island's northern and eastern shores. The eastern shore is marked by a series of peninsulas and inlets, notably Estero de Castro where the capital, Castro, is located. The western part of Chiloé Island, as well as the whole of Guafo Island, is hilly and covered by forests. The hills are subdivided into two north-south ranges, Piuchén and Pirulil, separated by the lakes Cucao and Huillinco. They contain the highest points in the archipelago, and do not exceed . Depressions in the western forest are occupied by numerous small lakes and bogs scattered across the landscape.