The Okinawa Trough(沖縄トラフ,Okinawa Torafu) (also called Chinese:中琉界沟, literally China-Ryukyu Border Trough ) is a seabed feature of the East China Sea. It is an active, initial back-arc rifting basin which has formed behind the Ryukyu arc-trench system in the West Pacific. It developed where the Philippine Sea Plate is subducting under the Eurasia Plate.