Galápagos Islands: Darwin's Living Laboratory in the Pacific

The Galápagos Islands are a volcanic archipelago in the Pacific Ocean, 1,000 kilometres west of the Ecuadorian coast, that have been shaped by the same geological forces that are still building them today. The islands sit above a hotspot in the Earth's mantle, and the Pacific Plate is moving slowly eastward over this hotspot, creating a chain of islands of increasing age from west to east — the westernmost islands of Fernandina and Isabela are still volcanically active, while the easternmost islands of Española and San Cristóbal are the oldest and most eroded.

Charles Darwin visited the Galápagos in 1835 aboard HMS Beagle and spent five weeks observing the islands' wildlife. The variations he noticed between the finches and tortoises of different islands — each population adapted to the specific conditions of its island — provided crucial evidence for his theory of evolution by natural selection, which he published 24 years later in On the Origin of Species. The Galápagos finches, now known as Darwin's finches, have become the most famous example of adaptive radiation in evolutionary biology.

The wildlife of the Galápagos is remarkable not only for its diversity but for its fearlessness. The animals evolved in the absence of land predators and have no instinctive fear of humans, which means that a blue-footed booby will continue its courtship dance as you walk past, a sea lion will investigate your snorkel mask with its whiskers, and a marine iguana will simply ignore you as it basks on the rocks. This lack of fear makes the Galápagos the finest wildlife-watching destination in the world — the animals are not hiding, not fleeing, and not performing for the camera.

The marine iguanas of the Galápagos are the only lizards in the world that feed in the sea, diving to depths of up to 12 metres to graze on algae on the ocean floor. They are found on all the islands and congregate in large groups on the rocky shores, piled on top of each other for warmth after their cold-water feeding dives. The males of the Española subspecies develop vivid red and green colouring during the breeding season, earning them the nickname 'Christmas iguanas'. Darwin described them as 'imps of darkness' — a characterisation that seems unfair given their extraordinary adaptation.

The Galápagos giant tortoises, which can weigh up to 400 kilograms and live for over 150 years, were once so numerous that sailors used them as a food source — their ability to survive for months without food or water made them ideal living provisions for long voyages. Hunting and the introduction of invasive species reduced the tortoise population from an estimated 250,000 to fewer than 15,000 by the 20th century. Conservation programmes, including the captive breeding programme at the Charles Darwin Research Station on Santa Cruz, have helped to stabilise and in some cases increase the populations of the most endangered subspecies.

Snorkelling in the Galápagos is among the finest in the world, with visibility of up to 20 metres and an extraordinary diversity of marine life. Sea lions play around snorkellers with the enthusiasm of puppies; Galápagos penguins — the only penguins found north of the equator — dart through the water at extraordinary speed; hammerhead sharks cruise in schools in the deeper water; and the green sea turtles that nest on the beaches are frequently encountered underwater. The cold Humboldt Current that flows north along the South American coast brings nutrient-rich water to the Galápagos, supporting a food chain of remarkable productivity.

Access to the Galápagos is strictly controlled by the Ecuadorian government, which limits the number of visitors and requires all tourists to be accompanied by a licensed naturalist guide. The most common way to visit is on a live-aboard cruise, which allows access to the more remote islands that cannot be reached on day trips from the inhabited islands of Santa Cruz, San Cristóbal, and Isabela. The best time to visit depends on what you want to see: the dry season from June to November brings cooler water and better snorkelling; the warm season from December to May brings calmer seas and the nesting of sea turtles and land birds.