The Tarbert-Killimer Ferry leaves every hour on the half hour and takes 20 minutes to cross the Shannon Estuary from North County Kerry to West County Clare; this saves you a 137-km (85-mi) drive through Limerick City. The ferry runs every day of the year except Christmas and costs EUR 17 one way, EUR 28 round-trip. (Ferries return from Killimer every hour on the hour.)
There are several options for traveling to the Oileáin Árainn (Aran Islands). Island Ferries runs a boat to the islands from Ros an Mhil (Rossaveal), 32 km (20 mi) west of Galway City, which makes the crossing in 20 minutes and costs about EUR 28 round-trip (or, weather permitting, you can opt for a boat that takes an hour, costing about EUR 20), including the shuttle bus from Galway; they also offer a ferry route between Doolin and the Aran Islands. Note that there's a handy ticket office in the TIO (Tourist Information Office) in Galway City. If you're heading for Inis Oirr (Inisheer), the smallest island, the shortest crossing is from Doolin in County Clare on Aran Doolin Ferries. Aran Doolin Ferries offers service from Doolin Pier, with up to 12 sailings daily, from June through the end of September. The crossing takes about 20 minutes and costs EUR 24 round-trip. Aran Direct goes from Doolin and Rossaveal and does interisland hops. Bicycles are transported free off-season, but there may be a charge in July and August: inquire when booking. There's lively competition between the ferry companies, so shop around for the best deal. Discounts are available for families, students, and groups of four or more. If you want to stay a night or two on the islands, ask about accommodations when booking your ferry, as there are some very good deals.
For travel between the Aran Islands, frequent interisland ferries (run by Island Ferries and Aran Direct) are available in summer, but tickets are nontransferable, so ask the captain of your ferry about the interisland schedule if you plan to visit more than one island; otherwise, your trip can become expensive. You can purchase ferry tickets on the island or at the TIO in Galway.
Island Ferries (Tourist Information Office, Forster St., Eyre Sq., Galway City. 091/568-903 or 091/537-700. www.aranislandferries.com). Aran Doolin Ferries (Doolin Pier. 065/707-4455. www.doolinferries.com). Aran Direct (Victoria Place, and 29 Forster St., Galway City. 091/506-786. www.arandirect.com). Tarbert-Killimer Ferry (065/905-3124. www.shannonferries.com).