Doolin is the most convenient departure point for the Aran Islands from County Clare. Doolin Ferry operates year-round sailings (weather permitting) to Inisheer, the smallest and closest island, as well as to Inishmaan and Inishmore. Inisheer can be visited as a day trip from Doolin — the ferry takes about 30 minutes and there is enough to see in a half day of walking the island.
For a more substantial Aran Islands visit, the overnight ferry to Inishmore from Galway city is the standard route, but arriving via Doolin gives you the pleasure of the Clare coastline on the approach. All three islands have an austere and genuine quality that is increasingly rare in rural Ireland — Irish is still spoken as a first language, the stone walls run in every direction, and the pace of life is noticeably different from the mainland.