The name Koufonisia spreads across a 26-square-kilometre municipal unit, but the land itself is modest and divided. Pano, or Upper, Koufonisi is the smallest of the group at just 5.8 square kilometres, yet the most densely populated, with 391 residents at the 2021 count clustered in the white settlement of Chora on its southwest coast. Kato, or Lower, Koufonisi lies just across a narrow channel, larger at 4.3 square kilometres but nearly empty, scattered with a few rural houses and one small church on a jetty. Beyond them sits Keros, uninhabited and protected. Where the name came from is itself disputed: some trace it to an old term for a sheltered, lee port; others to the many sea caves and hollows that riddle the islands' coasts.

Keros is uninhabited now, but it was not always so. The island is a protected archaeological site, and across the 20th century excavators drew from it a great quantity of ancient Cycladic art, the spare, abstract marble figurines whose clean lines influenced modern sculptors millennia after they were made. Human presence across the Koufonisia reaches back into prehistory. Digs at Epano Mili turned up evidence from the very first years of Cycladic civilization, including a striking pan-shaped vessel incised with a nine-rayed star, now held in the museum on Naxos. Later excavations on the eastern shore uncovered remains from Hellenistic and Roman times. These tiny islands have been inhabited, abandoned, and inhabited again for thousands of years.

Through the long centuries that followed, the Koufonisia shared the fate of the wider Cyclades, ruled in turn by Venetians and Ottomans who fought over the Aegean, especially through the turbulent 17th century. In that contest the islands' geography became their living. The narrow channel between Pano and Kato Koufonisi made a perfect hidden anchorage, and the islanders, by need or by choice, often threw in their lot with the fighters of the Mani and with the pirates who used the strait as a safe shelter. Only in 1830 were the Koufonisia freed along with the rest of the Cyclades and folded into the new Greek state, their long history of shelter and survival finally giving way to settled island life.

For all their beauty, these were hard places to make a living. After the Second World War and the difficult years of occupation, around a thousand people lived here, but many drifted to Athens for work, and men shipped out as deckhands on boats they did not own. For a long stretch a single doctor served the whole of the Lesser Cyclades, and in bad weather he could not even reach Koufonisia. Through it all, fishing endured. Pano Koufonisi still keeps one of the largest fishing fleets in Greece relative to its population, and the sight of caiques returning with the day's catch remains the island's defining image. Tourism has arrived in recent decades, but the sea, and the work of taking from it, came first.

The look of the Koufonisia is the look of the Cyclades distilled. Houses and walls are washed white and trimmed in blue, set deliberately against the boundless blue of the Aegean so that buildings and sea seem to dissolve into one another. A traditional island home held three rooms, a bedroom, a kitchen, and a larger living space, beneath a flat roof called a steosa, built up from reeds, wood, and packed earth. A white windmill on the east side of the harbour greets arriving boats. Faith and festival still order the year: Saint George processes over rose petals in April, fireworks light the Easter sky, and on the 15th of August the islanders cross to Kato Koufonisi for mass before racing their fishing boats home across the strait.