It's hard to appreciate what living and working in almost total darkness, blending to twilight, is like unless you've experienced it. No sunrises or sunsets, just days blending into days, lit by head torch or station.
Even on Macquarie Island at this time of year, there's only about six hours of daylight.
The winter solstice is a highlight of the Antarctic and sub-Antarctic calendar because it signals the slow withdrawal of the darkness and the return of sunshine, blue skies, day trips and animals.
"While Midwinter celebrations are a tradition dating back more than a century ago (around Mawson and Scott's heroic era of exploration), in more recent times we celebrate it to acknowledge that we are roughly halfway through our stay in Antarctica," Casey Station Leader Dave Buller said.
"We've made it to the shortest day of the year and are looking forward to seeing the sun in full flight again.
"Our Midwinter activities help boost team morale over a time where we are currently enduring dark and cold winter days."
A feature of the celebrations is the Midwinter swim. At Casey, Davis and Mawson, a hole has to be made in the ice using a digger or chainsaw, with curious Weddell seals sometime popping up to see what all the fuss is about.
Then, with air temperatures hovering around −20 °C, brave expeditioners assemble on the 'beach' and are lowered into water that's about −1.8°C.
"As seen in previous years, some will demonstrate a new-found skill of simultaneously entering and jumping out of the water at the same time," Dave Buller said.
"It's a somewhat brisk and confronting experience."
Casey research station is doing its swim a few days after the solstice this year because of extremely cold weather.
