Dunnottar Castle, . By far one of the most amazing sites in Scotland. The castle is perched on cliffs overhanging the North Sea and provides stunning views. The best way to get there for adventurous folk is the mile-long hike from the town of Stonehaven. The hike is a narrow path along the cliffs that provides stunning views the entire way and goes past the Stonehaven War Memorial. Definitely a must-see.edit
Stonehaven Harbour - The harbour forms what I would call the town center. There is a collection of local pubs and restaurants, though as it is a small town, we are talking about maybe 4 or 5 places. However, having a pint at a table overlooking the harbor and hanging with locals is a great experience. This town is very small, and in the town there are very few travelers, so it is a great chance to meet and talk to locals.
The Tolbooth Museum - Located on the Stonehaven Harbour covering the history of Stonehaven. Free entry.