Yedigöller owes its shape to a disaster. Landslides once choked this valley in the western Black Sea mountains, and the water that could no longer drain away settled behind the rubble as seven lakes in a row: Büyükgöl, Deringöl, Seringöl, Nazlıgöl, Kurugöl, İncegöl and Sazlıgöl. Surface streams and underground channels tie them to one another, so each basin rises and falls on its own schedule — and one of them, Kurugöl, is not there at all for much of the year. Turkey protected the valley as a national park on 29 April 1965. It is a small reserve, about 1,623 hectares, and nearly all of it is forest: oriental beech above all, threaded with hornbeam, oak, alder and elm, with fir and pine standing dark between them.
The path from lake to lake runs under a closed canopy the whole way, and no two basins hold the same colour: depth and the carpet of drowned leaves on the bottom turn one turquoise and the next a deep green. What draws the country north is the autumn. From mid-October to the first week of November the beech goes gold and copper, the oak and hornbeam turn rust, and the firs hold their green among them, so the slope reads as a mosaic rather than a single sheet of red. Cold nights leave mist lying on the water at dawn, and the reflection holds until the first breeze breaks it. That fortnight is also the park's problem. Autumn weekends overwhelmed a reserve this small, and since 2026 entry has been capped and runs by appointment.