Midwinter Day, the most prominent cultural holiday in Antarctica, it falls on 21st June.
Midwinter marks the southern winter solstice, which is the shortest day of the year. It is widely celebrated across nearly all international Research Stations as the halfway point of the harsh, dark winter. While it is not a legally mandated public holiday (as Antarctica has no indigenous population or government), overwintering scientists treat it as their most significant festive milestone.
The day is deeply steeped in tradition: For scientists and support staff overwintering on the ice, this day holds more significance than Christmas. Teams exchange handmade gifts, decorate their bases, and enjoy special multi-course meals prepared by their wintering chefs.
Stations tune into special radio broadcasts, including the annual BBC World Service Midwinter Broadcast. At several Australian and British stations, it is a quirky tradition for personnel to strip down and take a polar plunge in freezing, sub-zero waters. Heads of state and international programs traditionally send official Greetings, messages of goodwill to overwintering personnel.
The tradition was established by British explorer Robert Falcon Scott during his 1902 Discovery expedition. Scott wanted to boost morale by breaking up the monotony of the dark, freezing months, establishing a tradition that remains.