BY BOAT
There are regular ferries from Pireaus ( near Athens) and during the Summer season there is a daily Superjet service (hydrofoil) from Pireaus ( 3.5 hours).

From Santorini there are regular ferries to Folegandros ( and other islands) and there is a daily Superjet connection during the Summer season.

Check www.openseas.gr for schedules.

BY AEROPLANE

There is no airport on Folegandros ( there is a heliport). The nearest airport is Santorini. There are domestic connections from Athens with Aegean Airlines and Olympic Air.
There are direct flights from several European cities to Santorini during the Summer and charter flights operate from many countries also.