It's maritime custom for ships to fly the flag of the country whose waters they're in. This courtesy flag is a symbol of respect from a foreign vessel to its hosting nation, a token of goodwill and good faith.
When the British Australian (and) New Zealand Antarctic Expedition (BANZARE) set sail from London in 1929, Antarctica didn't have a flag. Not ones to shirk tradition, the crew improvised one. From the foremast, they hung a handsewn flag made from white cotton sheeting. The Times later noted the flag in the paper.
"The ship was flying the Union Jack at her forepeak, the white Antarctic flag at the foremast, and the Australian flag at the stern."
This makeshift flag later became known as the "White Flag of Antarctica." The crew raised the improvised flag once more on their final departure from Capetown in 1929, but since that day there have been hardly any recorded uses of courtesy flags in Antarctic waters. Until now.
A New Courtesy Flag
Nearly a century later, vessels in Antarctica once again have a courtesy flag. Expedition companies such as Oceanwide Expeditions and Arctic Tern Expeditions have adopted True South for their ships in Antarctic waters. True South is also traveling onboard vessels conducting research in the Southern Ocean as part of the scientific undertaking of national Antarctic programs.
Even when True South isn't flying from ships, it is still in some ways a courtesy flag. It will always be a flag for us to show our appreciation and respect for a land that is not our own. In so doing, it also serves to remind us that Antarctica is the common heritage of us all.