Locally chosen, not algorithmic. In rough order of "if you only do one thing".
Island
Arranmore Island
The largest inhabited island off the Donegal coast, 9km long, around 470 residents — a Gaeltacht community with a strong fishing tradition. Two ferries from Burtonport (15-minute crossing). The lighthouse on the north-west cliffs, the loop walk around the island, and Early's Bar in Leabgarrow are the headlines.
Good to know · Two competing ferry operators from Burtonport — both run year-round, more sailings in summer. Cars carried. Foot passengers welcome.
View
Mount Errigal
A 751m quartzite peak — Donegal's highest — rising in a perfect cone above the bog. The summit can be climbed in 90 minutes from the trailhead on the R251 between Dunlewey and Money Beg, but it's a serious mountain in poor weather. The view from the top runs across to Tory Island, the Bluestacks, and on a clear day the Sperrins.
Good to know · Free trailhead car park on the R251. Sturdy boots required, full mountain gear in winter. Check forecast — clouds the summit often.
View
Bloody Foreland
The north-westernmost tip of Gweedore, a low rocky headland looking out to Tory Island. The name comes from the colour the rocks take at sunset, when the granite catches the last light and turns blood-red. Drive the loop road, stop at the viewpoint, watch the sun go down over Tory.
Good to know · Free, always open. Free parking at the viewpoint. R257 loop is single-track in places.
Nature
Dunlewey and Poisoned Glen
A small Gaeltacht village at the foot of Errigal, on Dunlewey Lough, with the ruined Sacred Heart Church (built 1877, abandoned 1955) at its head. Behind it the Poisoned Glen — a U-shaped glacial valley, named (says one theory) for an Irish word mistranslated from 'heavenly' to 'poisoned' on a Victorian map.
Good to know · Free roadside parking at the church. The walk into the glen is rough, boggy, no waymarks beyond the start — for confident hillwalkers.
Town
Dungloe town
A small market town on the Dungloe river, with one main street, the Sweeney's Hotel since 1880, and the annual Mary from Dungloe International Festival in late July — a beauty pageant and ten days of music, going since 1968. Patrick MacGill, the 'Navvy Poet,' was born outside the town.
Good to know · Free parking on the main street. Big SuperValu. Tourist info in the centre.
Town
Burtonport
A working fishing harbour 5km north-west of Dungloe, departure point for the Arranmore ferries. Skipper's Bar on the pier for fish-and-chips while you wait for a boat. In its 19th-century heyday Burtonport landed more herring than any port in Ireland.
Good to know · Free parking at the pier. Cars on the ferry — pre-book in summer.