At 4588 km2, Isabela is the largest island in the archipelago and often touted by locals as the gem of the Galápagos. It is relatively young island given its proximity to the geological hot spot and consists of a chain of five active volcanoes: Volcán Wolf, the highest point in Galápagos at around 1700 m; Cerro Azul, whose last eruption was registered in 1998; Sierra Negra; Volcán Alcedo; and Volcán Darwin. 
Unfortunately, since many of the visitor sites are on the west side of the island and require a long passage (and fuel use) from Santa Cruz, few pre-arranged tours—limited to the larger, more expensive cruises visit Isabela. Although not a common visitor site for cruising, Isabela has recently gained popularity among visitors (and locals) as a side trip due to the island’s spectacular landscape and biodiversity.
The variety and abundance of avifauna in the various ecological niches of Isabela is especially notable. In the volcanic highlands, visitors can get close views of Galápagos hawks, flycatchers, and finches. In the island’s wetlands, visitors can see flamingoes, great blue herons, and sandpipers. And along the coast, visitors can spot penguins, cormorants, frigatebirds, and blue-footed boobies. Urbina Bay is a good place to see land iguanas, and you can also snorkel there. 
Isabela, can be accessed directly from Santa Cruz, by boat from Puerto Ayora. It takes about eight hours to get to Isabela via Floreana and about four hours to return. It is also possible to reach the island by plane from Baltra (30 minutes). Puerto Villamil, Isabela's main town is a much mellower version of Puerto Ayora and the second-most popular port to hang out in a hammock and watch the boobies fly by. True to island attitude, expect only the most basic tourist accommodations, restaurants, and bars.