Acarlar Longoz is a coastal barrier lake running parallel to the Black Sea coast between Sakarya's Karasu and Kaynarca districts, together with the floodplain forest around it. About 7.5 km long and 250 to 1,250 m wide, it is known as Turkey's largest continuous longoz forest. It takes about an hour to drive west from Akçakoca towards Karasu.
For part of the year the trunks of trees such as ash, alder and elm stand in water. In summer water lilies cover the surface of the lake; the water violet, found in Turkey only here, is one of the area's rare plants. Migratory birds such as herons, cormorants and wild ducks stop over and nest here.

The area was declared a first-degree natural protected area in 1998. In the section managed by Sakarya Metropolitan Municipality there are a wooden boardwalk through the wetland and viewpoints. The municipality announced that about 130,000 people visited the longoz in the three summer months of 2026.
Before you go
- The entrance fee and rowing-boat or pedalo tours vary by season; call Sakarya Metropolitan Municipality (153) before you go.
- For birdwatching, choose the early morning; binoculars make it easier.
- There are mosquitoes in the wetland in summer; bring repellent.
- On the way back you can see where the Melen River flows into the sea at Melenağzı; it's on the way.




