Dun Mercadale sits about 400 metres south of Loch Harport, and can be reached by a good track leading from the start of the Glen Brittle road. There is space to park beside the bridge, and the dun is already visible as a prominent eminence uphill.
This well ruined dun is girt by crags, but is easily scaled from the south (the path circles round to the south of the Dun). The summit is a grassy hollow, with plenty intermittent evidence of its bounding foundation course, a mixture of stone blocks and grassy mounds: though no sign of galleries. There appears to be the remains of an entranceway on the west. As usual, there is a fine aspect from the dun, along the length of Loch Harport.