structural:summarization, stylistic:style_transfer, information:extraction
Submarine

The Marmaray project, featuring a 13.7 km (8.5 mi) long undersea railway tunnel, opened on 29 October 2013. Approximately 1,400 m (4,593 ft) of the tunnel runs under the strait, at a depth of about 55 m (180 ft).

An undersea water supply tunnel with a length of 5,551 m (18,212 ft), named the Bosporus Water Tunnel, was constructed in 2012 to transfer water from the Melen Creek in Düzce Province (to the east of the Bosporus strait, in northwestern Anatolia) to the European side of Istanbul, a distance of 185 km (115 mi).

The Eurasia Tunnel is a 5.4 km (3.4 mi) undersea highway tunnel designed for vehicular traffic between Kazlıçeşme on the European side of Istanbul and Göztepe on the Asian side. Construction began in February 2011, and the tunnel opened on 20 December 2016.

Up to four submarine fibre optics lines (MedNautilus and possibly others) approach Istanbul, coming from the Mediterranean through the Dardanelles.