On the twelfth day of our tour, we visited the Sierra Negra volcano on Isabela island. This volcano has the second largest caldera in the world, after the Ngorongoro Crater in Tanzania. To get there, we went by bus, horseback, and finally on foot! We hiked down into a part of the volcanic landscape, and were treated to scenery that could only be described as "out of this world"! Only problem was that we needed to hike back out to get to the horses, and we understood then why some had nicknamed this the "Death March"!