Just down the coast from Sandycove is the charming seaside town of DALKEY (pronounced "dawky"), immortalized in Flann O'Brien's satirical novel The Dalkey Archive. On sunny days, the narrow streets and cliffside villas here have an almost Mediterranean lushness that makes Dublin itself seem a little cold and grey. Historically, Dalkey has thrived on comparisons with the capital: for two hundred years, it was the only natural harbour on the east coast of Ireland. Goods unloaded here filled Dalkey's warehouses and swelled its coffers, until the dredging of the Liffey in the sixteenth century wiped out its business and Dalkey dwindled to a village. In time, though, Dalkey's beauty ensured that fresh comparisons were made, as well-to-do Dubliners built seaside homes and the advent of the railway brought day-trippers with it. Today, its nostalgic old quarter merges into a commuter-belt hinterland under the cover of forested slopes and azaleas.

From Dalkey DART station it's a short walk down Railway Road to Castle Street, distinguished by two fortified warehouses from the fifteenth century, when Dalkey was dubbed the "Port of the Seven Castles". Goat Castle, across the way from Archibold's Castle, serves as Dalkey's town hall, with a visitor centre (Sat & Sun 11am–5pm, April–Oct also Mon–Fri 9.30am–5pm; €5) that features detailed exhibits on the town's history, set within the castle's impressive interior. If you're making the fifteen-minute walk from Sandycove to Dalkey, you'll pass a third fortification, Bullock Castle, built by the Cistercians in 1180 to protect Bullock fishing harbour.

From Castle Street you can take a lovely walk down Coliemore Road, past Georgian houses and Victorian villas, to Coliemore Harbour facing Dalkey Island, 300yd offshore. In summer there are daily boat trips, weather permitting, to the island, although it is advisable to phone in advance as even when the weather is fine the service can be a little erratic (tel 01/283 4298; €5 return). First inhabited 8500 years ago (the dwelling sites are marked by thickets of nettles), the island was known in Gaelic as Deiliginish (from which Dalkey derives), a name which recalls a spiked wooden fort (dealg means "thorn" or "spike") that once existed there. Here you'll find another Martello tower and the ruins of the medieval St Begnet's Oratory on the far side of the saddle-shaped island.

From Coliemore Harbour you can head south towards Killiney along the cliffside Vico Road to view the fabulous coastline. Steps and a path ascend steeply from Vico Road to Dalkey Hill, which is definitely worth climbing. There's an easier route off Sorrento Road via Knocknacree Road and Torca Road. On the latter road, Shavians can track down Torca Cottage, where George Bernard Shaw spent much of his boyhood; the house is privately owned, but a plaque on the wall acknowledges Shaw with his words, "The men of Ireland are mortal and temporal but the hills are eternal." En route to the summit, with its crenellated former telegraph station and fine views over Dublin Bay, you'll pass Dalkey quarry, from where the granite blocks that form the walls of Coliemore Harbour and the great piers of Dún Laoghaire were hewn.

To give your lungs a further workout, follow the partly wooded ridge up to Killiney Hill, where a stone obelisk enjoys even more glorious views, north to Howth and south to Killiney Bay and the Wicklow Mountains. From here, you can quickly descend to the park gate on Killiney Hill Road and refreshment at the cosy Druid's Chair pub; and then head down Victoria Road and Vico Road through the leafy and exclusive borough of KILLINEY, to reach the Killiney DART station in around fifteen minutes. The wide grey beach in front of the station runs the length of the four-mile bay to Bray.