Dozens of nude swimmers have braved the freezing waters of Canberra's Lake Burley Griffin to raise money for charity.
But some adventurous Australian Antarctic expeditioners took an even icier dip to celebrate the winter solstice.
The 66 participants in the ACT dropped their towels and plunged into the frosty waters at sunrise on Thursday, with the air temperature sitting at a frigid minus 3C.
Swimmers were asked to donate $30 to crisis support service Lifeline to participate in the second annual winter solstice swim, but many nippy dippers chose to chip in more.
Farther south, some 21 research station staff took a bone-chilling dive into Antarctic waters to mark the midwinter milestone.
With the outside temperate at minus 22C and water temperature at minus 2C, the staff honoured a mad tradition dating back to the days of early explorers such as Sir Douglas Mawson.
"Midwinter day is really important in Antarctica because it marks the halfway point of our year here on the ice and it means the sun will spend slightly longer in the sky each day," station leader Rebecca Jeffcoat said.
Australian Associated Press