Ask local advice during the deer stalking season (late Aug to late Oct)
Arran is a hill walker's paradise. The north part of the island boasts ten peaks of over 2,000 ft and dozens of ridge walks while the gentler south features a variety of less strenuous forest walks. Note that you should only attempt these routes in good weather and avoid climbing any rockfaces. Some ridge walks (A'Chir, Witches Step, Suidhe Fherghas and Cioch Na Oighe) involve quite a lot of scrambling and can be dangerous. They should only be attempted by fit and experienced climbers. Ropes and good OS maps should also be taken.
Goatfell
Arran's most popular peak, Goatfell, is also its highest, at 2,866 ft. There's a path leading up from Corrie, but most people begin the walk from the car park at Cladach sawmill, near Brodick Castle. The path is well marked, easy to follow and, apart from the final section, relatively easy. It runs initially through the Brodick Country Park, then follows the Cnocan burn as it rises steadily through woodland before crossing the Mill burn. Beyond the burn is a deer fence which runs across the entire island to keep the deer from the north away from the farming in the south. Above the deer fence the landscape changes to heather moorland and the path begins to climb the flanks of the mountain. The final 650 ft up to the top is steep and rocky and the path is not always clear. The last section requires some scrambling on loose scree but the views that greet you at the top on a clear day are magnificent, stretching right across from Ireland to Mull.
The walk to the summit and back should take about five hours. Though it's considered a fairly straightforward ascent, remember that this should be treated with the same caution and respect as any Scottish mountain. You should be dressed and equipped appropriately and be prepared for any sudden change in the weather. There are also numerous ridge walks around Goatfell as well as other high peaks to climb.
Glen Rosa
Many of the walks start from Glen Rosa Farm. One of these takes in the three Beinns; Beinn Nuis, Beinn Tarsuinn (2,681 ft) and Beinn A'Chliabhain. Start at Glen Rosa Farm and go up the Wood Road to the High Deer Gate, then to Torr Breac and the 'Y' junction at the top of the Garbhalt and on to the path which runs round the Three Beinns. This is a full day's walk.
Another excellent walk is from Glen Rosa to the head of the Glen; then take the path up into the Coire Buidhe and on to the ridge between Cir Mhor (2,617 ft) and A'Chir(known as the Ceems Ridge). Then follow the path around the west side of A'Chir. This is not easy to find, but takes you around the back of A'Chir to Bowman's Pass and the north end of Beinn Tarsuinn. From here take the path to Beinn A'Chliabhan and down to the foot of Garbhalt Ridge and back down to Glen Rosa.
Cir Mhor can also be climbed from Glen Rosa. Before going over into Glen Sannox take the steep path straight up. On the way back down, head into Coire Buidhe and back down the glen. You can also continue from the top of Cir Mhor and take the path around the west side of A'Chir to the north end of the Bowman's Pass up on to Beinn Tarsuinn and along the ridge to Beinn Nuis, then down the path to the Garbhalt Bridge.
Finally, you can also climb Caisteal Abhail (2,818 ft) from Glen Rosa. Go straight up into Coire Buidge on to the Ceems Ridge. Then take the path round the west side of the A'Chir through the Bowman's Pass and on to Beinn A'Chliabhain down the side of the Garbhalt to Glen Rosa.
Glen Sannox
There are also several walks in and around lovely Glen Sannox. It's a pleasant walk just to make your way up the head of the Glen and return the same way. You can walk up the Glen to beyond the old mine then make your way up towards the Devil's Punchbowl until you reach the main path and follow that down into the Coire. Take the main path back down into Glen Sannox instead of trying to climb out of the Devil's Punchbowl. You can also walk from Glen Sannox to Glen Rosa, which takes around four hours.