1. Winter solstice: December 21st marks the winter solstice, which is the shortest day and longest night of the year in the Northern Hemisphere. In Hawaii, this day translates to approximately 10 hours and 53 minutes of daylight.

2. Statehood Day: December 21st is also recognized as Statehood Day in Hawaii. On this day in 1959, Hawaii became the 50th state to join the United States. Many events and festivities are held throughout the state to celebrate this historic occasion.

3. Battle of Kuamoo: On December 21, 1819, the final battle between the anti-Christian supporters of the Hawaiian pagan religion and the Christian supporters took place on the Big Island of Hawaii. It resulted in the defeat of the pagan party and the establishment of Christianity in the Hawaiian Islands.

4. The Makahiki Festival: The Makahiki Festival is a traditional Hawaiian celebration that takes place from late November to mid-January, with December 21st falling at the peak of the festivities. The celebration marks the beginning of the Hawaiian new year, and it is a time of feasting, games, and worship.

5. Pearl Harbor Attack: December 21st is also significant in Hawaii history as it marks the anniversary of the Pearl Harbor attack. On this day in 1941, just weeks after the attack, it was announced that all civilians and troops living in the islands would be placed under military rule.