Acarlar Marsh

Acarlar Wetland Forest is a subas forest ecosystem located in northwestern Türkiye, between the districts of Karasu and Kaynarca in Sakarya Province. It covers an area of 1,562 hectares. Its length is approximately 7.5 kilometers, and its width varies between 250 and 1,250 meters. Its depth reaches up to 1.5 meters.

Acarlar Wetland Forest is the largest single-piece wetland forest (subas forest) in Türkiye and is notable for both its ecological diversity and geomorphological features. Located 6 kilometers west of the Sakarya River, the wetland drains its excess water into the Sakarya River via the Okçu Creek.

Acarlar Wetland Forest. (Ministry of Culture and Tourism of Türkiye)

Geographical Structure and Formation

Acarlar Wetland Forest is situated near the Black Sea coast, bordered to the north by sand dunes 20 to 25 meters high and to the south by low hills averaging 100 meters in elevation. The wetland exhibits the characteristics of a coastal barrier lake. This ecosystem formed over time through the accumulation of alluvial sediments carried by the Sakarya River and lagoons created by waves from the Black Sea.

Ecological Features

Tree species common in Acarlar Wetland Forest include hornbeam, European alder, beech, and black poplar. Much of the region is surrounded by hornbeam forests that can remain submerged seasonally. These forested areas adapt to seasonal fluctuations in water levels.

Approximately 2,300 plant species are found in the wetland. The water violet (Hottonia palustris) is an endemic species found only in this area. Numerous rare aquatic plants are also present, including the summer snowflake (Leucojum aestivum) and water lilies in yellow, white, and purple colors.

Fauna (Animal Diversity)

Acarlar Wetland Forest lies along a migratory bird route and provides habitat for 180 bird species, 147 of which are protected. Species such as the Eurasian spoonbill, common pochard, and wild duck are observed in the region. Among terrestrial fauna, mammals such as hare, fox, wild boar, badger, golden eagle, and squirrel are common.

Freshwater fishing is practiced in the wetland, with fish species such as pike, roach, carp, tench, and perch inhabiting the waters. Local communities also trade medicinal plants such as the water onion.

Acarlar Wetland Forest.(Ministry of Culture and Tourism of Türkiye)

Conservation Status

In 1998, the Acarlar Wetland Forest was declared a First-Degree Natural Site by the Bursa Council for the Protection of Cultural and Natural Heritage. In 2009, it was also registered as a Ramsar Site. As the only Wildlife Development Area in Sakarya, the wetland has been the subject of various planning initiatives aimed at conserving biodiversity and promoting sustainable use.

In 1971, the Adapazarı Water and Soil Organization widened the Okçu Creek, the wetland’s natural outlet, converting it into a canal. As a result of this intervention, approximately 40 percent of the lake area was lost.

Human Activities and Eco-Tourism

During summer months, when water levels recede, exposed areas are used by local communities for agriculture. Infrastructure including walking paths, restaurants, picnic and park areas, as well as boat and water bicycle tours, has been developed on the Karasu side of the wetland to promote eco-tourism.

A 750-meter-long boardwalk has been constructed for visitors. The area is favored for activities such as birdwatching, plant observation, and nature photography.

Acarlar Wetland Forest.(Ministry of Culture and Tourism of Türkiye)

Settlements and Access

Villages surrounding Acarlar Wetland Forest include Denizköy, Karamüezzinler, Üçoluk, Taşlıgeçit, and Camitepe in the Karasu district, and Turnalı, Büyükyanık, and Birlikköy in the Kaynarca district. It is approximately 50 kilometers from the center of Sakarya Province and about 26 kilometers from Karasu district.