Valentia Island

Where it sits. Valentia Island — Dairbhre, the oak isle — lies in Dingle Bay off the Iveragh Peninsula in south-west County Kerry, about 11 kilometres long by not quite three wide, which makes it the fifth-largest island off the Irish coast. It carries a permanent population of around 650, most of them in Knightstown at the eastern end and Chapeltown near the middle. Two links to the mainland exist: the Maurice O'Neill Memorial Bridge at Portmagee, open all year, and a short car ferry from Reenard Point to Knightstown that runs from April to October and cuts a long detour off the drive.

The story behind it. For a small island it has an outsized place in the history of communication. Valentia was the European terminus of the first commercially viable transatlantic telegraph cable. Attempts in 1857, 1858 and 1865 failed; success came in 1866, when a working cable ran from Foilhommerum Bay to Heart's Content in Newfoundland. Cables were worked from the island for a full century, until Western Union closed the station in 1966. The link had a scientific dividend few travellers hear about: before it existed, American longitudes were uncertain against European ones by some 850 metres, and in October 1866 an expedition set up a temporary observatory beside the cable station and exchanged the first transatlantic longitude signals, tying the two continents to a common frame of reference. The cable site now sits on Ireland's tentative list for World Heritage status.

Deeper history still. In 1993 an undergraduate geologist spotted fossilised tetrapod trackways in Devonian rock on the north coast at Dohilla — the prints of a primitive four-limbed vertebrate that crossed damp sand about 385 million years ago, when this ground lay in a river basin south of the equator. They are among the oldest evidence of vertebrate life on land anywhere, and they are simply there on the shore, roped off but open, free to visit.

On screen. Valentia has no Star Wars scenes filmed on it, and that distinction is worth keeping straight — the footage is out at Skellig Michael. What the island supplies is context and access. Boats to the Skelligs sail from Knightstown as well as Portmagee, and the Skellig Experience centre just over the bridge is the place where the monastery, the lighthouses and the seabird colonies are explained properly, using models and film rather than a boat ride. On days when the swell cancels every sailing — which happens often — this is where the trip goes instead.

What you actually see today. Geokaun Mountain is the island's high point, with a paid road running most of the way up and the Fogher Cliffs falling about 180 metres to the sea on the northern face; on a clear afternoon the view takes in the Blaskets, Dingle Bay and the Skelligs in one sweep. Glanleam House sits in sub-tropical gardens planted from the 1830s by the 19th Knight of Kerry, sheltered by windbreaks and effectively frost-free, holding tree ferns from New Zealand, Chilean myrtle and southern-hemisphere plants that elsewhere in Ireland need glass. The slate quarry above Knightstown, opened in 1816 and reworked since 1998, cut slate that roofed the Houses of Parliament; a grotto now stands in the old cavern. Cromwell Point Lighthouse, on the north-east tip, is open to visitors and stands on the site of a seventeenth-century fort.

Walking the island. The Bray Head loop at the western end climbs a grassy shoulder to another 1815 Napoleonic signal tower standing on a cliff about 240 metres above the water, with the Skelligs laid out to the south-west; it is a two-hour circuit on a well-worn but often muddy track, and the drop from the tower is unfenced. Shorter walks link Knightstown to the lighthouse and the old lifeboat slip. Valentia has kept a coast radio station and a lifeboat station for well over a century, and the island's heritage centre in Knightstown covers both alongside the cable story.

Weather and light. Valentia hosts one of the country's longest-running weather records and is on average the wettest station in Ireland, which is the price of a genuinely mild oceanic climate — snow and frost are rare, and the gardens exist because of it. Expect fast-moving fronts rather than settled days, and plan around squalls instead of waiting them out.

Getting there and timing. April to October is the practical window, when the Reenard ferry runs and the Skellig boats sail. The island is easy to drive but the roads are narrow, with passing places rather than two lanes on the climb to Geokaun. Knightstown, laid out in the 1830s with a neat terraced waterfront, has the concentration of guesthouses and pubs; Chapeltown and the bridge end are quieter. Anyone using a wheelchair will manage the Knightstown seafront, the Skellig Experience and the drive up Geokaun, but the tetrapod trackway path, the cliff edges and the lighthouse steps are not adapted.