Midwinter traditions in Antarctica live on as Australian expeditioners celebrate the year’s shortest day and longest night with a sub-zero swim through the sea-ice.

86 expeditioners are currently spending winter at Australia’s three research stations in Antarctica and on sub-Antarctic Macquarie Island.

Casey Station Leader Kyle Williams said Midwinter is a significant milestone for expeditioners because it marks ‘hump day’ in a long dark winter.

“At this time of year at Casey research station, the sun only rises above the horizon for about 2.5 hours, which can be challenging for our small wintering team of 27 people,” Mr Williams said.

“After we pass the winter solstice on 21 June, the sun begins to climb higher in the sky and we slowly start to get more daylight hours.”

Located further south than Casey, expeditioners at Mawson and Davis research stations are now living in constant twilight and darkness, with no sunrise for several weeks.

“A Midwinter tradition at Australian stations is an icy swim. We created a 1.5 metre square pool by cutting through the 80-centimetre thick sea-ice with chainsaws and other equipment,” said Mr Williams.

“The water temperature proved to be a bracing minus 2°C, and the air temperature of minus 9°C really got us moving.”

The swims are conducted under medical supervision and with safety equipment. Other Midwinter activities include a formal dinner and expeditioners giving each other home-made gifts.

Australian Antarctic Division Director, Kim Ellis, said the year since the last Midwinter celebrations has seen “dramatic” changes for Australia’s Antarctic Program to deal with the COVID-19 pandemic.

“We have been resilient and adaptive and kept all our research stations going strong and our expeditioners safe for another year,” Mr Ellis said.

“Our people deployed south and their families are always in our thoughts. Midwinter is an opportunity to have some fun as we reflect on how far we’ve come and what is yet to be achieved.”