The Biga River (Turkish: Biga Çayı) is a small river or large creek in Çanakkale Province in northwestern Turkey. The river begins at the base of Mount Ida and trends generally northeasterly to the Sea of Marmara. It is about 50 kilometres (31 mi) east of the Dardanelles. It flows past the towns of Çan and Biga and enters the Sea of Marmara at Karabiga.