State road D.400 (Turkey)

The D.400, also known as Antalya-Mersin Coastal Road, is a major east-west state road in Turkey. It runs along the Mediterranean coast, connecting the southwestern city of Antalya to the southeastern city of Mersin. It is one of the most important routes in southern Turkey, facilitating tourism, agriculture, and trade.

The road generally follows the coastline, offering scenic views of the Mediterranean Sea and the Taurus Mountains. It passes through several important cities and towns, including Kemer, Finike, Kaş, Kalkan, Fethiye (briefly connects), Demre, Kumluca, Gazipaşa, Alanya, Anamur, Aydıncık, Silifke, and Erdemli.

The D.400 is a two-lane highway for most of its length, although sections near larger cities may be widened to four lanes. Driving conditions can vary, with some stretches being winding and mountainous, requiring caution. The road is generally well-maintained, though landslides can occasionally cause temporary disruptions, particularly during the rainy season.

The D.400 is a critical artery for the transportation of agricultural goods from the fertile coastal plains to other parts of Turkey. It also provides access to numerous tourist destinations, making it a vital component of Turkey's tourism infrastructure. The route is frequently used by both domestic and international travelers.