The Galapagos islands consist of 13 main islands and over 100  smaller islets and rocks. The first are thought to have been formed between 5 and 10 million years ago. The islands are located at a geological hot spot, a place where the earth’s crust is being melted from below by a mantle plume, creating volcanoes. Because of this, several islands are still being formed as a result of volcanic eruptions.

Baltra: During WW II Baltra was established as a US Air Force base. Crews stationed at Baltra patrolled the Pacific for enemy submarines as well as providing protection for the Panama Canal. After the war the facilities were given to the government of Ecuador. Today the island continues as an official Ecuadorian military base. Until 1986, Baltra was the only airport serving the Galapagos. Now there are two airports, the other located on San Cristobal Island. However,  most flights operating in and out of Galapagos still fly into Baltra. During the 1930’s scientists decided to move 70 of Baltra’s land iguanas to the neighboring island of North Seymour as part of an experiment. This move had unexpected results for during the WWII military occupation of Baltra, the native iguanas became extinct on the island. During the 1980’s iguanas from North Seymour were brought to the Darwin Station as part of a breeding and re-population project and in the 1990’s land iguanas were reintroduced to Baltra.

Bartolomé: Named for Lt. David Bartholomew of the British Navy, this is a  small island located just east of Santiago Island. Desolate Bartolome is one of the most visited and photographed islands in the Galapagos. Bartolomé is an extinct volcano and has a variety of variably colored volcanic formations, including a tuff cone known as Pinnacle Rock. This large black partially eroded cone was created when lava reached the sea. Contact with sea water resulted in a phreatic explosion. The exploded molten fragments fused together forming a welded tuff. Bartolomé is inhabited by Galapagos penguins, sea lions, nesting marine turtles, white-tipped reef sharks and a variety of birds.

Darwin: This island is named after Charles Darwin. It has an area of 1.1 km² (0.4 mi²) and a maximum altitude of 168 m. (551 ft). Here fur seals, frigates, marine iguanas, swallow-tailed gulls, sea lions, whales, marine turtles, dolphins, red footed and Nazca boobies can be seen.

Española: The name was given in honor of Spain. It also is known as Hood island after an English nobleman. It has an area of 60 km² (23 mi²) and a maximum altitude of 206 m. (676 ft). Española is the oldest island and the southernmost in the archipelago. The island’s remote location has a large number of endemic fauna.  Secluded from the other islands, wildlife on Española adapted to the island’s environment and natural resources. Marine iguanas on Española are the only ones that change color during breeding season. The waved albatross is found on the island. The island’s steep cliffs serve as the perfect runways for these large birds which take off for their ocean feeding grounds near the mainland of Ecuador and Peru. Española has two visitor sites. Gardner Bay is a swimming and snorkeling site as well as offering a great beach. Punta Suarez has migrant, resident, and endemic wildlife including brightly colored marine iguanas, Española lava lizards, Hood mockingbirds, swallow-tailed gulls, blue footed boobies, Nazca boobies, Galapagos hawks, a selection of finches, and the waved albatross.

Fernandina: The name was given in honor of King Ferdinand of Spain, who sponsored the voyage of Columbus. Fernandina has an area of 642 km² (248 mi²) and a maximum altitude of 1,494 m. (4,902 ft). This is the youngest and westernmost island. In May 13, 2005, a new very eruptive process began on this island when an ash and water vapour cloud rose to a height of 7 km. (4.4 mi) and lava flows descended the slopes of the volcano on the way to the sea.The most recent eruption occurred on this island in April of 2009. Punta Espinosa is a narrow stretch of land where hundreds of marine iguanas gather largely on black lava rocks. The famous flightless cormorant inhabits this island and also Galapagos penguins, pelicans and sea lions are abundant. Different types of lava flows can be compared and the mangrove forests can be observed.

Floreana: This island was named after Juan José Flores, the first president of Ecuador, during whose administration the government of Ecuador took possession of the archipelago. It is also called Santa Maria after one of the caravels of Columbus. It has an area of 173 km² (66.8 mi²) and a maximum altitude of 640 m. (2,100 ft). It is one of the islands with the most interesting human history and one of the earliest to be inhabited. Pink flamingos and green sea turtles nest (December to May) on this island. The “patapegada” or Galapagos petrel is found here, a sea bird which spends most of its life away from land. At Post Office Bay, since the 18th century whalers kept a wooden barrel that served as a post office so that mail could be picked up and delivered to their destination –  mainly Europe and the United States –  by ships on their way home. At the “Devil’s Crown”, an underwater volcanic cone, coral formations are found.

Genovesa: The name is derived from Genoa, Italy where it is said Columbus was born. It has an area of 14  km² (5.4 mi²) and a maximum altitude of 76 m. (249 ft). This island is formed by the remaining edge of a large crater that is submerged. Its nickname of “the bird island” is clearly justified. At Darwin Bay frigate birds and swallow-tailed gulls, which are the only nocturnal of its species in the world, can be seen. Red-footed boobies, noddy terns, lava gulls, tropic birds, doves, storm petrels and Darwin finches are also in sight. Prince Philip’s Steps is a bird-watching plateau with Nazca and red-footed boobies. There is a large Palo Santo forest.

Isabella: This island was named in honor of Queen Isabela. With an area of 4,640 km² (1,792 mi²), it is the largest island of the Galapagos. Its highest point is Wolf Volcano with an altitude of 1,707 m. (5,600 ft). The island’s seahorse shape is the product of the merging of six large volcanoes into a single landmass. On this island Galapagos penguins, flightless cormorants, marine iguanas, boobies, pelicans and sally lightfoot crabs abound. At the skirts and calderas of the volcanoes of Isabela, land iguanas and Galapagos tortoises can be observed, as well as Darwin finches, Galapagos hawks, Galapagos doves and very interesting lowland vegetation. The third-largest human settlement of the archipelago, Puerto Villamil, is located at the south-eastern tip of the island.

Marchena: This island is named after Fray Antonio Marchena. It has an area of 130 km² (50 mi²) and a maximum altitude of 343 m. (1,125 ft). Galapagos hawks and sea lions inhabit this island, and it is home to the Marchena lava lizard, an endemic species.

North Seymour: Its name was given after an English nobleman called Lord Hugh Seymour. It has an area of 1.9 km² (0.7 mi²) and a maximum altitude of 28 m. (92 ft). This island is home to a large population of blue-footed boobies and swallow-tailed gulls. It hosts one of the largest populations of frigate birds. It was formed from geological uplift.

Pinta: Pinta got its name from one of the caravels of Columbus. It has an area of 60 km² (23 mi²) and a maximum altitude of 777 m. (2,549 ft). Swallow-tailed gulls, marine iguanas,  hawks and fur seals can be seen here. Also home to the world’s rarest living creature, the Pinta giant tortoise. An aged male named Lonesome George is the only known survivor. Since there is little hope of finding another specimen, his species is doomed to extinction.

Pinzón: Pinzón was named after the Pinzón brothers, captains of the Pinta and Niña caravels. It has an area of 18 km² (7 mi²) and a maximum altitude of 458 m. (1,503 ft). Sea lions, Galapagos hawks, giant tortoises, marine iguanas, and dolphins can be seen here.

Rábida: This island bears the name of the convent of Rábida where Columbus left his son during his voyage to the Americas. It has an area of 4.9 km² (1.9 mi²) and a maximum altitude of 367 m. (1,204 ft). The high amount of iron contained in the lava at Rábida give it a distinctive red color. White-cheeked pintail ducks live in a salt-water lagoon close to the beach, where brown pelicans and boobies have built their nests. Up until recently, flamingos were also found in the salt-water lagoon, but they have since moved on to other islands, likely due to a lack of food on Rábida. Nine species of finches have been reported on this island.

San Cristóbal: It bears the name of the Patron Saint of seafarers, “St. Christopher”. It’s English name was given after William Pitt, 1st Earl of Chatham. It has an area of 558 km² (215 mi²) and its highest point rises to 730 m. (2395 ft). This island hosts frigate birds, sea lions, giant tortoises, blue and red- footed boobies, tropic birds, marine iguanas, dolphins and swallow-tailed gulls. Its vegetation includes Calandrinia galapagos, Lecocarpus darwinii, and trees such as Lignum vitae. The largest fresh water lake in the archipelago, Laguna El Junco, is located in the highlands of San Cristóbal. The capital of the province of Galapagos, Puerto Baquerizo Moreno, lies at the southern tip of the island.

Santa Cruz: Santa Cruz is the name of the Holy Cross in Spanish. It has an area of 986 km² (381 mi²) and a maximum altitude of 864 m. (2834 ft). Santa Cruz is the island that hosts the largest human population in the archipelago at the town of Puerto Ayora. The Charles Darwin Research Station and the headquarters of the Galapagos National Park Service are located here. The GNPS and CDRS operate a tortoise breeding center here, where young tortoises are hatched, reared, and prepared to be re-introduced to their natural habitat. The Highlands of Santa Cruz offer an exuberant vegetation and are famous for its lava tunnels. Large tortoise populations are found here. Black Turtle Cove is a site surrounded by mangroves which is used as a mating area for sea turtles, rays and small sharks. Cerro Dragón, known for its flamingo lagoon, is also located here, and along the trail one may see land iguanas foraging.

Santa Fé: This island is named after a city in Spain, and has an area of 24 km² (9 mi²) and a maximum altitude of 259 m. (850 ft). Santa Fé hosts a forest of Opuntia cactus, which are the largest of the archipelago, as well as  Palo Santo. Weathered cliffs provide a haven for swallow-tailed gulls, red-billed tropic birds and shear-water petrels. Santa Fé species of land iguanas are often seen, as well as lava lizards.

Santiago: It’s name is equivalent to Saint James in English; it is also known as San Salvador, after the first island discovered by Columbus in the Caribbean Sea. This island has an area of 585 km² (226 mi²) and a maximum altitude of 907 m. (2976 ft). Marine iguanas, sea lions, fur seals, land and sea turtles, flamingos, dolphins and sharks are found here. Pigs and goats, which were introduced by humans to the islands and have caused great harm to the endemic species, have been eradicated (pigs in 2002; goat eradication is nearing finalization). Darwin finches and Galapagos hawks are usually seen, as well as a colony of fur seals. At Sullivan Bay a recent (around 100 years old) pahoehoe lava flow can be seen.

South Plaza: It is named in honor of a former president of Ecuador, General Leonidas Plaza. It has an area of 0.13 km² (0.05 mi²) and a maximum altitude of 23 m. (75 ft). The flora of South Plaza includes Opuntia cactus and Sesuvium plants, which forms a reddish carpet on top of the lava formations. Iguanas (land and marine and some hybrids of both species) are abundant and there are a large number of birds including tropic birds and swallow-tailed gulls which can be observed from the cliffs at the southern part of the island.

Wolf: This island was named after the German geologist Theodor Wolf. It has an area of 1.3 km² (0.5 mi²)and a maximum altitude of 253 m. (830 ft). Here fur seals, frigates, Nazca and red- footed boobies, marine iguanas, sharks, whales, dolphins and swallow-tailed gulls can be seen. The most famous resident is the vampire finch which feeds on the blood of the boobies and is only found on this island.