Air
During the summer, Aegean and Olympic fly daily—or even twice a day, depending on the period—to Skiathos from Athens International Airport. The trip takes 45 minutes. In summer there are also weekly flights from Athens and Thessaloniki to Skyros Airport; the flights take 40 minutes. Fares vary dramatically depending on how far in advance you book.
Skiathos Airport also has direct flights from many European cities.