Achill is the simplest island to add to an Ireland itinerary because you never need a ferry: the Michael Davitt Bridge at Achill Sound links it to the mainland on the R319, about 30 minutes past Westport in County Mayo. The Atlantic Drive loop around the southern coast, past Keem Strand and Dooega, takes a steady half-day. Book a hotel in Westport or Newport rather than on the island itself if you want restaurant choice in the evening; Westport gives you the Greenway and a bigger base for Connemara day trips.
Achill Island: The One You Can Drive To
Come between May and September for the best chance of dry weather, though the wind never really stops. Keem Strand has a car park and a steep walk up to the cliffs; Dooagh and Dugort are quieter strands. Skip Achill in February unless you specifically want emptiness, because many cafés and activity providers close. Fuel up before the bridge: petrol stations on the island are limited.
The Aran Islands: Inis Mór, Inis Meáin and Inis Oírr
The Aran Islands sit across Galway Bay and are reached by ferry from Rossaveel, roughly 45 minutes' drive west of Galway city, or from Doolin in County Clare on a shorter crossing. Inis Mór is the largest, with Dún Aonghasa fort and its cliff edge, and suits a full day or an overnight. Inis Meáin is the quiet middle island, good for walking and nothing else in a hurry. Inis Oírr is the smallest and closest to Doolin, with a wreck on the shore and a compact village.
Sailings are weather-dependent and can be cancelled at short notice, so build a spare day into your plan rather than booking a tight onward connection. Book a hotel in Galway city for the Rossaveel option; the drive out on the R336 takes about 45 minutes. Summer weekends fill up, and the islands are busiest between June and August. Bring cash for small cafés, wear shoes you can walk on stone in, and skip the pony-trap touts if you prefer to walk the lanes yourself.
Valentia and the Kerry Coast
Valentia Island is joined to the mainland by a bridge at Portmagee on the Ring of Kerry, and by a car ferry at Knightstown in summer; the bridge is the reliable option year-round. The drive from Killarney takes about an hour. The island holds the Skellig Experience centre, the slate quarry and the lighthouse at Cromwell Point. Portmagee is the departure point for boat trips to Skellig Michael, which run roughly May to September and depend entirely on sea conditions.
Treat Valentia as a half-day to a day rather than a destination. Stay in Kenmare, Cahersiveen or Killarney and drive out; Kenmare gives you the best evening choice of restaurants and easy access to the Beara Peninsula. Book Skellig boat trips well ahead for July and August, and accept that a cancellation is a real possibility. Skip the ferry crossing if you are short of time; the bridge does the same job in five minutes.
Rathlin Island, off Antrim
Rathlin lies six miles off the north Antrim coast and is reached by a foot-passenger ferry from Ballycastle, a crossing of about 25 minutes. Cars are limited and you rarely need one: the island is small, with the Kebble cliffs and a seabird colony in spring and early summer. Ballycastle is about an hour and a quarter from Belfast on the A2 coast road, and the Giant's Causeway is a short detour on the way back.
Go between April and July for puffins and nesting seabirds, and check the ferry timetable before committing, as sailings are tied to tides. Book a hotel in Ballycastle or Bushmills if you want to be close to the port, or in Belfast if you are combining the island with the city. Skip Rathlin if you have only a single day on the north coast, because the ferry times eat into it; the cliff path at Fair Head on the mainland gives you a similar view for less planning.
Which Island to Choose
If you want one island with the least friction, choose Achill: no ferry, no weather risk, and a strong base in Westport. If you want the classic Atlantic experience, choose Inis Mór from Rossaveel and give yourself two nights in Galway. If you want scenery and boats, Valentia with a Kenmare base. Pick Rathlin only if your trip already includes the Causeway coast. All four are best between May and September; Achill and Valentia remain workable in the shoulder months, while the Aran and Rathlin crossings are more likely to be disrupted by wind.
