Sapanca is a county of Sakarya province. It has Sapanca Lake in the north, the city centre of Sakarya, Adapazarı in the east, Samanlı Mountains, Gevye and Pamukova counties in the south and city centre of Kocaeli, İzmit in the west. Its floor area is 140 km2, its height from sea is 36m. Sakarya is the smallest county in terms of area, but the biggest in terms of population density. When it comes to climate, it precipitates aboundly in the winter and this precipitation is in the form of snow generally. The winters are hot and wet.
The soils of the county can be divided into two parts: The first part consists of the northern outskirts of the Samanlı Mountains which are the extensions of Köroğlu Mountains in the southern part of Bolu, and the valleys in these outskirts. This part is pretty rugged. The second part is the mountain skirt plain in the northern outskirts of Samanlı Mountains where the city centre is located. This plain consists of the alluviums carried by the rivers flowing from the mountains. .
The most important rivers are İstanbul River, Kurtköy River and Mahmudiye River. Furthermore, the most important river Akçay River connects to the Sakarya River. Northern Anatolia fault line passes from Sapanca Lake. For this reason, the county is first degree earthquake region. However, since the fault line passes from the lake, the county centre and other settlement areas affected from the earthquake less. Because of this reason, the county was mildly impaired from the 17 August 1999.
According to known written documents, when Phrygians came to the region in B.C. 1200, Sapanca became a settlement place but its real foundation was in A.D. 378 by Bithynia Kingdom. Siphonensis Lacus name was firstly used in Laz resource in 391 for the first time. In the Eastern Roman Empire period, Buanes, Sofhan and Sofhange names were used.
When Anatolian Seljuks came to Sapanca region, they called it Ayan and Ayanköy. After the Crusades, the region was conquered by the Byzantines. When Evliya Çelebi passed from this region in 1640 on his way to Erzurum, he wrote these lines about he town: Since when old man from İzmit cleaned the forest and bushes, and plowed, a village called Sabancı Koca (Old Plower) is settled. Then, through time, it developed and became a town in the time of Suleyman the Magneficient. Sarı Rüstem Paşa constructed a khan with 170 rooms in the town. It has a nice mosque, hamam and bazaar. Its imarets are covered by sky lead. There are nearly 1000 houses with tiled roofs. All the imarets are work of Mimar Sinan. Another Mimar Sinan work is Pertev Paşa khan. Since this work is a charity work and belongs to Rüstem Paşa, it is administered by the committee of the foundation. This place had a janissary chief-in-command. Its white cherry is famous.
There is a bakery near the hamam. A dervish used to cook and bless a kind of white bread which is very famous with the name of Sabanca Somun. This bread does not go bad and lose its taste even after 40 days. It is so famous that they took it to the Persian Shah and he also liked it. Some says that it is due to the water that it is so delicious. There is also a village.
In 1837, in the time of Mahmut II, Adapazarı become a city centre. Sapanca became a county of this city. İzmit - Bolu highway used to pass from Sapanca. Kâtip Çelebi, in his Cihannüma book, told about Sapanca part of this road that for one mile, the road passes from the water and when it is rainy season, it reaches the stirrup.
The same description was made by Charles Texir in the first half of the 19th century. For one hour, the vehicle goes on the sand of the lake. In some places, the water reaches the column of the vehicle. The railway that was constructed in 1890 was built by openning a space in that region. When railway was constructed, highway was neglected and became nearly departed.
In the time of the Republic, the highway passed from the mountain skirts, not from the narrow passage at the lakeside. Thus, the town continues to enable both land road and railway transportation. When E-5 Highway passed from the other side of the lake, Sapanca lost its importance for a short time but when TEM Motorway passed from the county in 1989, Sapanca acquired its historical mission again.