The zonally aligned Rio Grande Rise separates the Argentine Basin in the south from the Brazil Basin in the north. It is a high topographic obstacle for bottom water propagation to the north. Two meridional gaps intersect the Rise at ~39° W and ~28° W (Vema and Hunter channels, respectively). The depth in the Vema Channel exceeds 4,600 m as compared to the background depths of 4,200 m. The Hunter Channel is much shallower and the greatest depth does not exceed 4,000 m.