Aono Raina High Sea

West of the southern Line Islands, the surface waters of the South Equatorial Current move across the open Pacific. Beneath them, near four degrees south, a branch of the Southern Subsurface Countercurrent carries water eastward at roughly 250 metres' depth. A second, deeper branch lies farther south. These currents form part of a Pacific-wide system of subsurface jets whose oxygen-rich water can be traced far from its source.