It's unlikely altitude sickness will ever be an issue when climbing Donegal's peaks, but what they lack in height they more than make up for in beauty and scenery. As challenging as you want to make them, they are not to be taken lightly with sufficient levels of fitness required. As with most mountains they can be made more difficult depending on the route you choose to take, from gradual to steep climbs, to scrambling over loose boulders and scree, so always plan your route in advance and know your own limits. For the most part a reasonable level of fitness and the necessary hiking equipment is all that's required.
Donegal has two main mountain ranges, the Derryveagh mountains in the middle of the county and the Bluestack mountains to the south (see map below). There are a number of peaks in each of these ranges worth climbing as elevation can sometimes offer the best vantage point for viewing Donegal. Depending on where you are staying however, access and transportation may limit your options.
Two of the more well known peaks are located in the Derryveaghs, Errigal (An Earagail in Irish) and Muckish (An Mhucais). Errigal is Donegal's tallest peak standing at 751 metres, while Muckish is slightly lower at an elevation of 666 metres. Muckish is famous for its table top summit which lends itself to the name, An Mhucais, which in Irish translates as pigs back. It's said that when viewed from the north west side, the mountain resembles a pig lying down.
Both of these peaks form the beginning and end of what are known locally as the 7 sisters. This is row of peaks that stand out in the skyline when viewed from the Falcarragh direction or while driving from Glenveagh to Dunlewy along the R251 on your right hand side.
From north to south, the 7 peaks include, Muckish, Crocknalaragagh, Aghla Beg, Ardloughnabrackbaddy, Aghla More, Mackoght and finally Errigal. A worthwhile trek, however there is a significant amount of ascending and descending involved so be pre-warned. Schedule your hike in advance and ensure you have enough daylight hours to complete it. If not, bring a light tent or bivvy bag, break up your journey and enjoy a night under the stars...
Donegal's 6 highest peaks: (Click on the links below for more detailed information on some of the popular climbs.)