A23A. Sailing by the largest iceberg around.

Under the quill, the sea bottom two to three thousand meters deep rapidly rises to an oder of magnitude smaller.  

From the early morning, to our starboard, a white line covers the horizon. EUROPA sails fast again today, and before the watch change at eight is when she is the closest to the 30 to 50 meters high vertical ice wall that extends for 40 by 30 nautical miles along the flat topped A23A. One of the largest and most well-known tabular icebergs in the Southern Ocean nowadays. 

The beginning of its history dates back to 1986, when it broke off the Weddell Sea Filchner–Ronne Ice Shelf. An area about 3,900 square kilometers made it one of the largest icebergs in the world. Quiet and steady at first, it started its drift in 2020. Today we met it aground when EUROPA sails over the steep change on depth between the abyssal plains and the South Georgian Continental Shelf.  

It hasn’t been an easy voyage for such a large iceberg. In November 2023, it was tracked moving past the northern tip of the Antarctic Peninsula heading to the Circumpolar Current. But once more its wanderings got to a standstill five months later when got trapped in a sort of Eddie on the oceanic flow near the South Orkney islands, 375nm from the Antarctic Peninsula. So far not travelling further, A23A started to turn counterclockwise by around 15 degrees every day. It was just recently when this huge mass of ice resumed its journey, now heading towards South Georgia, until touching ground 45nm from the Southwest of the island. 

Resembling a Noah’s arch, such a mega-scale iceberg brings with it a whole ecosystem at the same time that disturb the wind patterns, temperatures around them, water salinity, ocean currents, transfers of heat and moist between atmosphere and the water surface, thus reaching the point of creating their own local weather. The ice that builds them has been traveling for many years from the depths of the Antarctic Continent to the shoreline, loading itself with dust and minerals from land. 

Upwelling of rich deep waters around them as they hit their steep sides and follow them to the surface, plus the introduction to the marine system of those minerals and nutrients that hey transport, fertilise their surroundings for the phytoplankton.  

Intertwined to the huge amount of ice, some communities of microorganisms, microalgae, crustaceans, fish, find their habitat. A rich one indeed that attracts birds and whales, as we could see today when we sailed just a handful of miles along it. 

But A23A's home lays far south from here, in the depths of the Weddell Sea on the second largest ice shelf on Earth, after the Ross Sea. An area that was discovered during the German scientific expedition led by Wilhelm Filchner on board the ship Deutschland in 1911, their findings revised and extended by the Ronne Antarctic Research Expedition in 1947–48. 

Filchner focus was to explore and study the unknown coast far East in the Weddell sea. A voyage that brought to the world the discovery and mapping of new Antarctic territories, the furthest south achieved at the time, the discovery of the Filchner ice shelf, and one of the most important oceanographic findings that shapes the Southern Ocean, the Polar Front. 

Sailing by such large and well studied iceberg was the highlight of the morning, but still, the evening brought another one, the arrival to her next destination. The high mountains of South Georgia, the island’s northwest corner, show up now and then between the low clouds and light rain. Sailing with the veering winds, EUROPA keeps her canvas set until shortly before her anchor drops in the 20 meters deep area of Right Whale Bay. A welcoming quiet night after her fast and bumpy ride from Antarctica to South Georgia.