The largest of the islands, Isabela is made of six shield volcanoes and is home to a huge variety of wildlife. From the wide and endless beaches in the south to the young and still developing coral beaches in the west, to the lofty peaks of Volcan Wolf at 5600 feet, it hosts a multitude of mini eco-systems, as is the norm in most of Galapagos. The town of Puerto Villamil is the second largest in the archipelago. Here too is the lava field of the 'aa' type which is home to the biggest colony of marine iguanas. The infamous "Wall of Tears" built by hand, stone by stone by the unfortunate wretches of the prison colony is also on this island.