Settlers and explorers
Two kinds of voyage stand out in Greek history. The first is colonisation, in which groups of Greeks left their home cities and founded new communities overseas. The second is exploration, in which a traveller set out to learn about distant coasts. Both depended on seafaring skill, but they had different goals. The dates and details come from later writers and archaeology, and many are uncertain, so approximate centuries are used here.
The age of colonisation
From about the eighth century BCE, Greek cities sent out colonies, a movement that lasted around two centuries. The word colony can mislead. These settlements were usually independent cities, though they kept ties of religion and sentiment with the mother city, the metropolis. Reasons given in ancient sources and modern studies include land shortage, political conflict, trade opportunities and the pursuit of metal sources. The mix probably varied from case to case.
A group of settlers was typically led by a founder, chosen by the home city, and often consulted the oracle at Delphi before departure. The voyage itself was made in ships of the types described in the article on Greek ship design, probably with a mix of warships or cargo ships, though details are poorly documented.
Western Mediterranean
In the west, Greeks settled in southern Italy and Sicily, an area later called Magna Graecia. An early site was Pithekoussai, on the island of Ischia in the Bay of Naples, usually dated to the earlier eighth century BCE. Syracuse in Sicily was traditionally founded by settlers from Corinth in 733 BCE, though the date comes from later tradition and should be seen as approximate. Further west, Phocaean Greeks founded Massalia, now Marseille, around 600 BCE, and it became an important trading city on the coast of southern France.
The Black Sea and the north Aegean
To the north-east, Greek settlers founded cities around the Black Sea, including Sinope on the southern shore and Olbia on the northern coast. Byzantion, later Constantinople, is traditionally dated to the seventh century BCE. The motive here was often access to grain, timber, fish and metals, and the Black Sea ports became an important source of supplies for Athens and other cities. Getting there meant passing through the Hellespont and Bosporus, where strong currents posed a challenge for ships.
North Africa
In North Africa, Greek settlers from the island of Thera founded Cyrene, traditionally around 630 BCE, on the coast of modern Libya. It grew into a wealthy city. Greek settlements in Egypt were more limited, but Naukratis in the Nile Delta developed as a trading centre under permission from the pharaohs.
What the voyages involved
The sailing of the colonising ships was seasonal, with spring and summer favoured. Settlers needed provisions, tools, seed and religious objects. Once at the new site, they chose a place with a harbour, fresh water and farmland. They often had to deal with local peoples, with relations that ranged from trade to conflict. Archaeology shows that Greek settlement was not uniform and that local communities shaped the outcome.
Pytheas of Massalia
The best-known exploratory voyage is that of Pytheas, a Greek from Massalia, who lived in the later fourth century BCE. He is reported to have sailed beyond the Pillars of Heracles (the Strait of Gibraltar) and along the Atlantic coast to Britain and further north. His own work, usually called On the Ocean, is lost, and we know it only through quotations and criticism by later writers, some of whom doubted him.
According to these reports, Pytheas described Britain and its tin, mentioned the Baltic region and its amber, and wrote about a land called Thule, six days’ sail north of Britain. He is also reported to have noticed that the length of day varied with latitude, and that the tides were linked to the moon. The identification of Thule is uncertain, and suggestions include Norway, Iceland and the Shetland Islands. Whether he made all the journeys himself, and how far he went, is debated. Because the original text is missing, any account of his voyage is tentative. His interest in tin links to the wider theme of tin trade routes.
Other Greek voyages
Greek tradition also remembered legendary expeditions, most famously the voyage of the Argonauts to the Black Sea. This is myth, though it may reflect memories of early contact with the region. Historical explorers included the Carian Skylax, who is said to have sailed down the Indus at the order of the Persian king Darius, though the account is uncertain. Hellenistic rulers later sponsored voyages down the Red Sea, in part to obtain war elephants.
Why they matter
These expeditions reshaped the Greek world, spreading the Greek language, cults and trade across the Mediterranean. They also created the conditions for the later growth of Greek merchant fleets and the wider Mediterranean seafaring system. At the same time, the evidence is uneven. Foundation stories were written down long after the events, and archaeology only partly confirms them. The result is a picture that is broadly reliable in outline and uncertain in detail.