Dunskey is protected on three sides by cliffs while the landward side is protected by a 15m wide rock-cut ditch, once crossed by a drawbridge. In the vaulted entrance there are remains of a stone bench, doorways on either side of the passage lead to small guardroom on the left and a larger vaulted chamber to the right.
The passage opens into what was a large courtyard, probably once lined with buildings but now reduced to lumps and bumps in the long grass. In the eastern corner stands the ruin of an early 16th century, L-plan tower-house with a square stair tower in the angle The door is at the foot of the stair tower, above it there are three empty panels.
The ground floor is vaulted, the main block has cellars, the wing has two narrow vaulted chambers, one of which may have served as a prison. All are accessed from a central passage, except the northernmost which is entered from the courtyard. At the opposite end there is a mural stair communicating with the hall above, and was probably used as a wine cellar.
A wide scale and platt stair in the wing led only to the 1st floor, thereafter access was by a turnpike stair within the square tower, the remaining three floors of the wing where occupied by what we can assume to be bedrooms, each with it own fireplace. The wide stair was a later addition, previous which the turnpike had served all floors The hall fireplace was in the west wall, to the right of it a large window faces into the courtyard, and on the left is the doorway leading into the stair tower.
At the far end of the hall a door leads into the 17th century extension above the courtyard entrance, having only one fireplace, this appears to have been one long room, possibly a gallery. The floor above the hall has a mural chamber at the eastern end, to the left of the window, to the right one moulded fireplace jamb survives. The chamber was probably a latrine closet serving the lord's bedroom, there are no others. There was an attic floor above this.
The shape of a round oven, with a drain alongside, can be made out among the lumps and bumps which were once the courtyard buildings. Dunskey was built around 1510 by the Adairs of Kilhilt. It replaced an earlier building which had been plundered and burned by Sir Alexander McCulloch of Myrtoun, Keeper of Falcons to James IV, in 1489 after laying siege to the castle and starving out its defenders. It was extended and remodelled by Viscount Montgomery, who was laird between 1608 and 1634. It passed to the Reverend James Blair in 1648, but was ruinous as early as 1684. The castle is accessible but not 'open to the public': entry is at your own risk.
A cliff-top footpath leads from the south end of Portpatrick's waterfront.