The location is Rancho Mariposa in the highlands of Santa Cruz. It's a good place to see giant tortoises. They come here on their own at certain times of the year. The rancher, who is also a naturalist, gives them free access to the ranch.
Tagus Cove and Darwin Lake from a point above the lake. The Beagle anchored in the cove for a day while looking for water. Despite the name, this is not the hypersaline lake Darwin described. That lake is somewhere south of this location. Fernandina is visible in the far distance.