The Izu-Ogasawara Trench (伊豆・小笠原海溝, Izu-Ogasawara Kaikō), also known as Izu-Bonin Trench, is an oceanic trench in the western Pacific Ocean, consisting of the Izu Trench (at the north) and the Bonin Trench (at the south, west of the Ogasawara Plateau).