Less than an hour's travel time south of the Black Sea city of Trabzon lies Altindere National park. Much smaller than the usual interpretation of a national park, Altindere puts itself on the map because it's home to the area's biggest tourist attraction, the Greek Orthodox Sumela Monastery.
With a bevy of tour providers in Trabzon and the much closer Maçka, most will have a guide to provide a bit of background to this religious structure, despite the fact that the first glimpse of it as you emerge from the either the wooded trail or the roadway is hard to describe in words. Luckily, we can rely on photographic evidence of this 4th century monastery, which is built about 1,200 m high into the flank of a mountain and reached via 300 or so steps from the valley floor. The view from below is breathtaking, while the frescoes (despite having sustained serious damage) and the various rooms in which monastic life has been performed are highlights of the interior.
There are a number of local trails available for hiking, although the park office can't always be depended on to have maps since travelers usually arrive via tour bus intent only on seeing the monastery. There are also bungalows on-site for overnight stays, although it's a short ride to and from Maçka and public transport is available to the park entrance.
If you're looking to be anywhere in northeastern Turkey, then the cultural attraction of the Sumela Monastery and the verdant peaks in which it's situated are a fine proposition.