You can reach Skiathos
With flyingcats, ferryboats and dolphins from Agios Konstantinos, Volos and Mantoudi.
If you live in Athens you can reach one of the two ports by your own car or by bus from Omonia. The distance Athens – Agios Konstantinos is 165 km. From there, calculate 1.5 hours to Skiathos by speedboats (they do not carry cars or motorbikes) or by ferryboats that do almost twice the time. From the port of Volos the distance is reduced to one hour by speedboats, while you will calculate almost twice an hour by conventional ferry.