THE PLAN BEFORE THE KEYS
Travel lightly. Give the island time.
Sikinos has a quieter character, a clifftop Hora and a landscape of terraces, chapels and walking routes. The transport question starts with where you are staying and which walks or coastal outings you want to make. Ask your accommodation about current connections and arrival transfers.
A provider in the directory names Sikinos as a service area, but no Sikinos fleet examples are in the checked catalog. Establish current local operation directly rather than assuming a car is waiting at arrival. A smaller itinerary can make a short rental or a prearranged transfer more sensible than keeping a vehicle throughout the stay.