It could be the fresh air and the friendly, easy-going, open-door lifestyle. It could be fresh vegetables and goat's milk.
It could be the mountainous terrain. Everywhere on Ikaria is up, or down, so getting around keeps you fit.
It could even be the natural radiation in the granite rocks. But Stamatis Moraitis thinks he knows what it is.
"It's the wine," he says, over a mid-morning glass at his kitchen table. "It's pure, nothing added. The wine they make commercially has preservatives. That's no good. But this wine we make ourselves is pure."
Stamatis celebrated his 98th birthday on New Year's Day. He says he's older, but his documents put his date of birth as 1 January 1915. Outside his whitewashed house are his beloved olive trees, his fruit trees, and his vines. He makes about 700 litres of wine a year, he says.
The remainder of the article can be found here together with some more photographs and a video of the interview with Stamatis