The Orhangazi Tunnel (Turkish: Orhangazi Tüneli), is a motorway tunnel located at Samanlı Mountains in Marmara Region as part of the Istanbul-Bursa Motorway O-5 in Turkey.

[1] Situated northeast of Orhangazi town between Laladere and Yeniköy villages on the province border of Yalova and Bursa,[2] it is a twin-tube tunnel of length 3,586 and 3,591 m (11,765 and 11,781 ft) carrying three lanes of traffic in each direction.

The construction works began on 15 February 2012,[2] and are being carried out by Otoyol A.Ş., a consortium of Turkish Nurol, Özaltın, Makyol, Yüksel, Göçay and Italian Astaldi companies.

[4][5] Breakthrough in one of the tubes was achieved on 19 February 2014 after two years and four days of work.

A related ceremony was held at site in presence of Deputy Prime Minister Bülent Arınç and Minister of Transport, Maritime and Communication Lütfi Elvan on 3 March 2014.