Sakarya
Lake Sapanca (Sapanca Gölü) is a freshwater lake in the eastern Marmara region, in Sakarya and Kocaeli provinces. It is about 16 km long and 5 km wide and covers roughly 47 km². The town of Sapanca lies on the southern shore, below the Samanlı Mountains. The lake supplies drinking water to Sakarya and Kocaeli.
In Sapanca the lakeshore is a few minutes' walk from the railway station. Sapanca Park, a walking and cycling path, runs about 6 km along the shore from Kırkpınar. The calm water suits rowing and canoeing. Sakarya İl Ormanı Nature Park, on a hill above the lake, has viewing terraces. Nearby Maşukiye belongs to Kartepe district in Kocaeli, not to Sapanca.
Sapanca is about 135 km from İstanbul by the TEM motorway. The Ada Ekspresi regional train between Gebze and Adapazarı stops at Sapanca; Marmaray connects at Gebze. The municipality recommends April–May and October–November. The shore paths are flat. Check train times with TCDD first.