This report summarizes geological and geophysical data from the deep-water (greater than 200m) region of the St. George Basin lease sale area #70. The shallow-water region is discussed in detail by Marlow and others (1979a) in a companion report. The triangular deep-water region lies at the junction of the Bering shelf and the Aleutian Ridge (Fig. 2). This region is bounded on the northeast by the 200 m bathymetric contour that defines the edge of the Bering shelf, on the southeast by a meandering line that lies 3 miles north of the Aleutian Islands, and on the west by the 171°W longitude meridian. Hereafter, this triangular region is referred to as the Umnak Plateau region. The name is derived from a major bathymetric feature, Umnak Plateau, that covers most of the region.