triangular-shaped ocean area covering a large portion of the floor of the Gulf of Mexico. The basin lies northwest of the Campeche Bank, approximately between 22° and 26° N and 89° and 95° W. Depths range beyond 11,000 feet (3,400 m) in much of the area, with Sigsbee Deep (17,070 feet 【5,203 m】) being the deepest point. In the middle of the basin, the Sigsbee Knolls form a series of hills that are believed to be reflections of underlying salt domes rising above the generally flat basin floor.