This is where the water wrestles with itself.
Nature has drawn a loopy circle through the Southern Ocean well away from, but around, Antarctica. The line wanders anywhere from north of 47 degrees latitude to south of 60 degrees, and meanders from season to season, year to year. It’s where the deep-chilled brine of polar surface water slips beneath the warmer waters of the north. The result of the battling waters is the Antarctic Convergence.
Although it is a virtually invisible – and somewhat shifting – line, the Convergence forms perhaps the most imposing quarantining of species in the world. Consider that in an area larger than North America there are just 39 of the more than 9,000 species of birds on the planet. This time of year the Convergence – alternatively, the Polar Front – sees surface waters around Antarctica become diluted with fresh water from ice melt.
The mix and churn of the warm and saltier water from the north with colder Antarctic water conjures up great blooms of algae. Tiny shrimp-like krill feed on the algae, and then become the main staple of dinners for everything from penguins to whales. On board a ship, there’s no noticeable difference from the convergence itself beyond a dip in temperature. While the Convergence is often associated with violent seas, the roller coaster conditions are often just a coincidence.