Roca Union, once connected to the island of Isabela, offers great views of Sierra Negra and Cerro Azul. Although we cannot land on this site, our zodiacs will pass through the area on our way to Los Tuneles in order to better observe the island’s residents, like the marine iguanas, blue-footed boobies, Nazca boobies, and Sally Lightfoot crabs. According to geologists, Roca Union was directly connected to the Sierra Negra volcano, whose lava formed the large rock formation thousands of years ago.