Do I need transportation to enjoy Skiathos?

You certainly do not need transport to enjoy beauties of the island. Skiathos isn't a big island and you can go anywhere fast and easy using local transportation (bus, taxi or water taxi). Also, there are daily excursions to various scenic areas of the island. However, a transportation would give more freedom to you. Especially if you live outside Skiathos Town or you would like to visit distant beaches. If you decided not to take your car with you, there's always the possibility to rent a car, motorcycle or boat from the local rentals.