The following D'ni holidays are listed with their approximate Gregorian calendar-equivalent dates. Because of the slight differences in length between the D'ni hahr and the Gregorian year, the actual dates may be shifted a day or two off of the date listed here, depending on the year.
List of holidays
First Feast of the Maker
Lenovoo 10 (March 27)
This celebration, like the other two that share its name, pre-dates the D'ni's arrival on Earth, and there is no information regarding the rituals performed on this day, or what its specific purpose was. Based on the description, it was likely a religious holy day dedicated to celebrating the D'ni god Yahvo.
Leefo 1 (April 21)
The First Common Library Opened
Leefo 12 (May 5)
It is currently unclear whether this was a celebrated holiday, or simply an anniversary of the opening of the first common library in the D'ni cavern, which occurred on this date in 233 DE.
Second Feast of the Maker
Leebro 20 (June 21)
The Day of Dancing
Leetar 21 (September 3)
"Remarkably a day that one would think would not be the cause for celebration was turned into one by the D'ni. The First Day of Dancing marks the day that their old home was completely and utterly destroyed. Ever since their exodus the world was apparently on a destructive path, and after three and a half thousand years the world was not only uninhabitable, but completely destroyed. The D'ni turned the news into a celebration. They celebrated the Great King who taught them to seal that old world from their hearts, as well as the fact that they were able to exit that world and continue their lives on earth, instead of being destroyed with their former home.
First Arrival of the Great King
Leevot 12 (September 28)
Given the lack of knowledge regarding the Great King at the time of the fall of D'ni, this day was probably not widely celebrated as a holiday by the D'ni people. Whether it was an old celebration that simply lapsed, or another key event that Cyan wished to commemorate is presently unknown. However, the DRC celebrated the occasion with a poetry contest in 2003, so perhaps the holiday has been given new life.
Third Feast of the Maker
Leevofo 18 (November 11)
Leevofo 27, November 23
Like other specific events listed here, it is unknown if this corresponds to an actual holiday that continued to be celebrated by the D'ni up until its fall, or if it was simply another day on the calendar (like Presidents Day in the United States).
Finding of the Lost Books of Birenni
Leevobro 12, December 12
This holiday sprang from the discovery of the Lost Books of Birenni in 2262 DE, as the name of the holiday implies. These Books were ancient Ages written by Birenni, which belonged to the Guild of Healers, and were re-discovered during a time when D'ni was being ravaged by a terrible plague. Something in one of these Ages provided the D'ni with a way to defeat the plague, and from that time forward, the D'ni celebrated the anniversary of their discovery by hiding firemarbles in their homes for children to find (much like Easter egg hunts), reminding them of the search that the King and his wife undertook to find a cure for their people.