On the morning of November 14, 1963, sailors south of Iceland saw something that looked at first like a ship on fire. A dark column was rising from the North Atlantic. It was not smoke from a vessel but volcanic ash and steam, blasted upward by an eruption that had begun beneath the sea.
Within a day, new land stood above the waves.
The island was named Surtsey, after Surtr, the fire giant of Norse mythology. The eruption continued intermittently until June 1967, building a volcanic island where open ocean had existed only a few years earlier. For geologists, it was an extraordinary chance to watch an island being constructed almost from birth. For biologists, it offered something even rarer: a piece of new land on which they could observe the arrival of life step by step.
That opportunity came with an unusual rule. Humans would have to stay away.
An island born 130 meters below the sea
Surtsey lies in the Vestmannaeyjar, or Westman Islands, volcanic system off Iceland's southern coast. According to the Surtsey Research Society, the eruption probably began several days before anyone saw it, on the seafloor at a depth of roughly 130 meters.
When rising magma met seawater, the interaction was explosive. Rapid cooling fragmented the magma into volcanic ash and other tephra, while enormous clouds of steam and debris burst above the surface. By November 15, enough material had accumulated for an island to emerge.
The early island was vulnerable. Loose volcanic ash is easy prey for North Atlantic waves, and the sea began dismantling Surtsey even while the volcano was still building it. Lava flows later covered parts of the island, forming tougher armor. Meanwhile, heat and water altered some of the loose volcanic glass into palagonite tuff, a much more resistant rock.
Those processes helped Surtsey survive. Many volcanic islands born in the ocean vanish quickly after eruptions end. Surtsey became durable enough to remain above water — and important enough that scientists immediately began documenting almost everything that happened to it.
This is also why describing Surtsey as an island that repeatedly “disappears and reappears” is misleading. It has continuously existed above sea level since 1963. What is true is almost as dramatic: the island is slowly being eaten by the ocean, and its coastline has changed enormously since its birth.
The experiment that scientists were forbidden to contaminate
Biologists quickly recognized the scientific value of keeping Surtsey as free as possible from deliberate human influence. Iceland protected the island in 1965, while the eruption was still underway. Tourist landings were prohibited, and access remains tightly controlled today.
The logic is simple. If visitors carried seeds in their boots, insects in equipment, soil on clothing or food that attracted animals, scientists would lose the ability to distinguish natural colonization from human introduction.
Even researchers operate under restrictions. Scientific expeditions are permitted for monitoring and carefully designed studies, but the purpose of the reserve is to allow geological and ecological processes to proceed with minimal disturbance. Icelandic authorities prohibit unauthorized landing, introduction of organisms, minerals or soil, and activities that could alter the site.
That has turned Surtsey into one of the world's longest-running natural experiments in primary succession: the development of an ecosystem on newly created ground that initially lacks soil and established terrestrial communities.
UNESCO recognized that value in 2008 by adding Surtsey to the World Heritage List. Its significance is not merely that the island is young, but that scientists have an unusually continuous record of what happened after its formation.
How does life reach a completely new island?
Life began arriving almost immediately, although not always in the order people might imagine.
Diatoms were among the early colonists recorded around the coast in 1964. Seeds and fragments of plants washed ashore with ocean currents. Some seeds collected from the new beaches could still germinate after their journey through salt water.
In spring 1965, scientists recorded the first higher plant growing on Surtsey's shore: sea rocket. Other coastal pioneers followed, including species whose relatively large seeds can float and tolerate seawater. The likely sources included Iceland's southern coast and neighboring islands.
Other organisms arrived by air. Wind can carry spores, microscopic organisms and lightweight biological material across large distances. Birds transported seeds and invertebrates intentionally or accidentally. Floating debris provided another natural ferry across the ocean.
Scientists initially mapped individual vascular plants, marking their positions and following their growth. Eventually there were too many plants for that approach, so researchers established permanent plots where they could monitor vegetation, soils and invertebrates over time.
UNESCO records show how rapidly diversity accumulated. The first vascular plant appeared in 1965, ten species had established during the first decade, and by 2004 researchers had recorded 60 vascular plant species, alongside dozens of bryophytes, lichens and fungi. Hundreds of invertebrate species have also been documented.
Birds changed the experiment
The colonization of Surtsey was not simply a steady procession of seeds landing on sterile rock. Once animals began using the island, they changed the conditions for everything that came afterward.
Seabirds were particularly important. Birds bring marine nutrients onto land in their droppings, carry organic material and disturb the ground. Where colonies become established, nutrient-poor volcanic surfaces can develop richer soils and denser vegetation.
In other words, the arrival of one group of organisms changes the probability that others can survive. Plants provide shelter and organic matter. Invertebrates arrive and reproduce. Birds fertilize the soil. Microorganisms alter nutrients. An ecosystem begins to engineer itself.
This is one of Surtsey's great scientific lessons. Ecological succession is not simply a list in which species A arrives, then species B, then species C. It is a web of feedbacks in which each new colonist can modify the habitat inherited by the next.
Seals also began visiting the young island and eventually used its shores as resting and breeding habitat. Marine life colonized the underwater lava and rocky coast at the same time that terrestrial communities developed above sea level. Surtsey's experiment therefore extends from microbes in soil to algae beneath the waves.
The island is shrinking while scientists watch
Surtsey was largest near the end of its eruption. In 1967 it covered about 2.7 square kilometers. The North Atlantic has been cutting it down ever since.
The Surtsey Research Society describes severe wave erosion, particularly during powerful winter storms. In the first years after the eruption, several hectares could disappear annually. More recently the loss has slowed to roughly a hectare per year on average. A 2025 research review reported an island area of about 1.2 square kilometers in 2019 — less than half the maximum area measured when volcanic activity ended.
UNESCO considers erosion part of Surtsey's natural evolution rather than a defect to be repaired. The island is supposed to change. Waves attack cliffs, storms rearrange beaches, the ground subsides and volcanic material consolidates into harder rock.
The softer parts will continue to disappear. UNESCO assessments have projected that much of the remaining erodible island will eventually be removed, leaving a more resistant core. Lava flows and palagonitized tuff are the reason Surtsey has not already suffered the fate of many temporary volcanic islands.
So Surtsey is not a permanent island in the ordinary human sense. It is a process caught in mid-motion: volcano building upward, ocean cutting downward, rock hardening, plants spreading and animals continually altering the biological landscape.
A place humans protect by almost never visiting
Most famous natural places are protected so people can experience them without destroying them. Surtsey represents almost the opposite philosophy. Its scientific value depends on keeping ordinary visitors off it.
That restriction creates an unusual paradox. The island belongs to a UNESCO World Heritage Site precisely because the world has agreed not to treat it like a normal tourist attraction. Researchers can visit under controlled conditions, but for everyone else the best way to preserve Surtsey is to observe it from a distance.
The experiment has now been running for more than six decades. Scientists know when the ground emerged, what the original volcanic substrate looked like and when many of the early colonists arrived. Few natural ecosystems come with such a clear starting date.
Surtsey therefore gives researchers something close to a time-lapse film of ecology. A seed crosses the sea. A plant survives. Birds arrive and fertilize the ground. Invertebrates find new habitat. Soil develops where there was once only volcanic debris. At the same time, the ocean removes pieces of the laboratory itself.
The island's most remarkable story is not that it appeared from nowhere. Volcanoes have created islands before, and they will do so again. What makes Surtsey exceptional is that humans recognized, almost immediately, that the best experiment was to resist the urge to interfere — and simply watch what life did next.
