The recent increased activity associated with offshore oil and gas exploration and production in the outer continental shelf and slope regions of the northern Gulf of Mexico (GOM) calls for a better understanding of the ocean circulation in these regions and the potential environmental effects of those activities. Safe operation of offshore facilities during exploration and production is required for the protection of human life and the marine environment. Moving into deep water places the oil and gas operations closer to strong surface-intensified currents associated with the Loop Current (LC) and LC rings. Sub-surface current measurements over the northern continental slope provide evidence of vigorous currents and Topographic Rossby Waves. In the deep GOM below 1000 m, vertically homogeneous currents are observed to intensify near the bottom.