Although the largest island in the archipelago, Isabela is a relatively young 1 million years old. It was formed by the uplifted lava flows from six major shield volcanoes: Ecuador, Wolf, Darwin, Alcedo, Sierra Negra and Cero Azul. All except Volcán Ecuador remain active, making Isabela one of the most volcanically active places on earth. The most recent eruptions were: Wolf in 1982, Cerro Azul in 1998 and Sierra Negra in 2005.
There are a number of species endemic to Isabela including the world’s only surviving population of mangrove finch. The island's topography has allowed giant tortoises to evolve into distinct sub-species and, indeed, Volcán Alcedo is home to the largest population in the Galapagos. Unfortunately, the stately reptiles must compete for the limited foodstuffs available with a population of some 50,000 or more feral goats.
The island's only town, Puerto Villamil, is located at the southeastern tip of the island and is the archipelago’s third largest human settlement. This sleepy little village of pastel coloured houses is situated on an attractive white sand beach. Although most Galapagos cruise boats do not stop here, it is a good starting point for land-based tours.
The narrow Bolivar Channel that runs between Isabela and Fernandina Island is one of the best places to see whales such as Bryde’s whale and, reasonably frequently, Orcas or killer whales. Pods of bottle-nose dolphins can usually be relied on to put on a display for passing boats.
The island offers many fascinating landing points. Tagus Cove was for 300 years
an anchorage favoured by pirates and whalers and is now a superb spot for
snorkelling. The interesting results of more volcanic activity can be found at
Urbina Bay where in 1954, a strip of Isabela’s west coast rose some 16 feet
leaving much marine life stranded half a mile inland when the new coastline was
formed. The islets of nearby Elizabeth Bay are visited by panga as this is
really the only way to explore the red, black and white mangroves, which are
home to many species of birds, mammals and marine life.