By Jon Donnis
More than 2,000 years ago, a Greek explorer sailed into the northern Atlantic and reported reaching a mysterious land called Thule. Since his original account has been lost, nobody knows exactly where Thule was. Iceland, Norway, the Faroe Islands and the Shetland Islands have all been suggested, but the mystery remains unresolved.
The story begins with Pytheas of Massalia, a Greek explorer from the city that is now Marseille. Around 330 BC, Pytheas travelled beyond the familiar Mediterranean world and explored the Atlantic coast of Europe and Britain. He recorded his journey in a work called On the Ocean, but the book has disappeared. What survives comes from later writers who quoted or summarised parts of his account.
According to those surviving descriptions, Pytheas reached Thule after travelling for several days north of Britain. He described it as being close to what he called the frozen sea. He also reported unusual conditions caused by the extreme northern latitude, including remarkably long periods of daylight during summer.
For people living in the Mediterranean world, these observations must have seemed extraordinary.
Pytheas appears to have encountered people living in Thule, and descriptions of their way of life provide some of the few clues about where he might have been. Grain was apparently grown in the region, although the climate meant it had to be processed indoors. Other accounts mention plants, roots, berries and honey.
The problem is that these clues can be interpreted in several different ways.
Iceland is perhaps the most famous candidate for Thule. Its northern position would fit some of Pytheas's observations, particularly his descriptions of unusual daylight. However, there is a significant difficulty. There is no generally accepted evidence for a permanent human settlement in Iceland at the time of Pytheas's voyage. If his account of meeting inhabitants is accurate, Iceland becomes harder to reconcile with the evidence.
Norway is another possibility. Parts of the Norwegian coast fit the descriptions of climate, agriculture and daylight rather well. Some historians have therefore suggested that Thule may have been somewhere in central or northern Norway rather than an isolated island in the Atlantic.
The Faroe Islands have also been proposed, while the Shetland Islands became associated with Thule in later geographical writing. The problem is that later writers did not necessarily use the name in precisely the same way as Pytheas had done.
This may explain why the mystery has proved so difficult to solve.
Thule gradually became more than a geographical location. To later Greek and Roman writers, Ultima Thule became a phrase representing the furthest known place in the world. The expression was eventually used in literature to describe the distant edge of civilisation and exploration.
That transformation is significant because the original Thule may have been a very real place, even though its identity has been lost. Pytheas was not simply describing a mythical land at the end of the Earth. His journey appears to have taken him into regions that were genuinely unfamiliar to the Mediterranean world.
His observations of daylight and latitude are particularly interesting because they suggest that he was making genuine geographical observations rather than inventing a fantasy. Later writers sometimes treated his claims with suspicion, but modern understanding of the northern environment shows that several of his observations are entirely plausible.
There is even uncertainty over the name itself. Some modern interpretations have suggested that Thule could have been connected with a word describing mist or fog, potentially reflecting the strange atmospheric conditions Pytheas encountered. That remains a theory rather than an established explanation.
Ultimately, there may never be a definitive answer.
Thule could have been a particular island, part of the Norwegian coast, or another northern location that was later confused with different places. The original evidence has been filtered through centuries of writers who never saw the land themselves.
What makes Thule so compelling is therefore not simply the possibility of finding a lost island. It is the glimpse it provides into a world that, to the ancient Greeks, lay almost unimaginably far beyond the boundaries of the known world.
For more than two millennia, the name has survived even though the place itself remains uncertain. Thule became the edge of the map, the ultimate northern frontier, and perhaps one of history's most enduring geographical mysteries.
