The Canton Trough is an extremely deep linear feature flanked by large en echelon ridges. This system, located in the equatorial Central Pacific Basin, can be traced ENE from the Phoenix Islands for a distance of more than 500 km. The surrounding topography is lineated parallel ot the ridge-trough-ridge system and probably originated by block faulting. A similiar mode of formation is inferred for the main trough itself, the implication being that the vertical displacement may exceed 3000 m in some localities. This interpretation is reinforced by the occurrence near the base of the trough of an unusually diverse assemblage of igneous rocks, including normal oceanic tholeiitic basalts, coarse-grained diabases, anorthositic gabbros, pegmatitic gabbros, and cumulate gabbros. Simple vertical displacements of crustal blocks also could produce the major components of the observed gravity anomaly signatures as well as explain the necessity in the gravity models for a crustal root beneath the Canton Trough. Sediments within the Canton Trough region are predominately radiolarian oozes and calcareous turbidites, which correlate with transparent layers and highly stratified units observed on reflection profiler records. Magnetic studies of the region reveal 650-&ggr; residual anomalies, which are at least partly produced by the great topographic relief of the ridge-trough-ridge zone. However, the anomalies appear to obliquely cross the structural fabric and extend beyond the bathymetric terminus of the trough and ridges. This configuration indicates that some components of the magnetic signatures are generated by another mechanism. Although there is some evidence that the Canton Trough and its surrounding structures represent an extension of the Clipperton Fracture Zone into the Central Pacific Basin, the absence of structural continuity, the lack of regional depth changes, and the limitations imposed by the regional tectonic patterns argue against this hypothesis. It is possible that the Canton Trough zone was created by an abrupt change from the Phoenix spreading direction to that inferred across the Manihiki Plateaus.