Nivocissat Nascya
The Nivocissat Nascya, "Lakelight Nights" in Dryzhky, is an annual tradition held in northern Ztavsk meant to memorialize those lives lost to the frigid waters of the Rozhivy Nivoc, "Old Man's Lake" in Dryzhky. The exact date varies from year to year but observation of the holiday begins on the first new moon after the vernal equinox. Despite the relatively somber impetus for the tradition, the atmosphere during the Nivocissat Nascya is in fact quite jovial.
Before the holiday officially begins, pilgrims from all over Ztavsk, and occasionally from further beyond, congregate in one of the three major cities that sit on the banks of the Rozhivy Nivoc. Other settlements along the lake shore observe the Nivocissat Nascya as well, but they do not often attract visitors from outside during this time of year. Only those who have blood ties or who grew up in these villages will visit for the holiday.
Festivities begin with a feast on the first of the three Nivocissat Nascya nights. This feast is held in honor of the living and is meant to nurture the bonds between close friends and family as well as to welcome visitors from afar who come in kinship to remember those that have been lost. The second night is a comparably more somber affair. Under the faint glow of the tiniest sliver of moonlight, close relations of those who have been swallowed up by the waters of the Rozhivy Nivoc send small wooden boats carrying lit candles, small mementos, and short messages for the departed into the lake. As these boats float away, they come to resemble twinkling stars in the dark of the moonless night.
The third night is another festive occasion. A second feast is thrown but this time it is in honor of the departed. Tales are told at every table about the lives the people lived before the lake claimed them in order to keep their memory alive.
I like the way you've woven the lake into this tradition.