While the Beagle was taking soundings on the outer coast of Chiloe, Darwin and Mr. King rode across the island from San Carlos to Castro, and then on to the Capella de Cucao on the west coast. The road crossed a succession of hills and valleys, with a forest of lofty trees on either side, in which numerous dead tree trunks stood like great white skeletons, apparently killed in a "bad wind".
The pair reached the pretty quiet town of Castro, and proceeded south, following the coast. At Chonchi they crossed the island, following “intricate winding paths, sometimes passing through magnificent forest opening into pretty clearings planted with corn & potato.” At Vilinco they reached the lake of Cucao, twelve miles long and running east and west, bordered by unbroken forest. Cucao was the only inhabited place on the west coast of Chiloe. North of P. Huantamò it became extremely rugged, with roaring breakers.
Returning across the lake, they left Castro early in the morning. Upon entering the forest, they had a memorable view of the Corcovado and Lagartigas volcanoes, from the brow of a steep hill. After bivouacking under a cloudless sky, they reached San Carlos the following morning.