Shortly after the boat crossed the Antarctic Convergence
, a major zone of depression was rising in the south, on track to wallop the boat with winds reaching sixty knots.
The Antarctic Convergence
, which encircles Antarctica roughly 1,500 kilometres off the coast, divides the cold southern water masses and warmer northern waters.
In 1963 and 1964, scientists on two Antarctic research cruises of the vessel Eltanin found so many specimens of Gigantocypris muelleri in the waters of the Antarctic Convergence
region (where antarctic surface waters and deeper subantarctic waters meet) that they suggested using the creature's presence as an indicator of the area.