On a steep, green-sided crag about 7km inland from the town stand the ruins of Ünye Castle, founded by the Pontics and rebuilt by the Byzantines. There's an ancient tomb cut into the rock face below.
Driving towards Tokat, you'll see the rear of the crag from the road, but access to the site is around 1km down the lane and then a stiff climb. Taxis from central Ünye charge around ₺50 return depending on waiting time. Minibuses to Kaleköy, Akkuş and Niksar drive past the access lane junction on the D850.