Wikipedia
In Hawaiian legend, Nightmarchers (huaka'i pō or "Spirit Ranks," '' 'oi'o) are the ghosts of ancient Hawaiian warriors. On the nights of Kane, Ku, Lono, Akua, or on the nights of Kaloa they are said to come forth from their burial sites to march out to past battles or to other sacred places. They march at sunset and just before the sun rises. Anyone living near their path may hear chanting and marching, and must go inside to avoid notice. They might appear during the day if coming to escort a dying relative to the spirit world. Anyone looking upon or seen by the marchers will die unless a relative is within the marcher's ranks- some people maintain that if you lie face down on the ground they will not see you. This is to show respect. However, if exiting the area is the fastest option, it is recommended. Placing leaves of the ti (Cordyline'' sp.) around one's home is said to keep away all evil spirits, and will cause the huaka'i pō to avoid the area. Another thing is to always highly respect the night marchers which can result in great things.
The ceremony and conduct of the march is customised to the tastes of its honored leader. A chief known to be fond of music would be honored with much drumming and chanting. If the chief enjoyed peace and quiet, the march would be as silent as possible. If a chief did not like to walk around much, he would be carried in a sling. In old Hawaii, laws declared parts of a chief to be sacred, and not seen. The punishment for looking at these parts was death. If a chief's face was not supposed to be seen, he would lead. If his back was not to be looked upon, he would be in the back. However, for some chiefs, there was no part of them that was forbidden to look at. This chief would march among the other warriors in the group.
There are gods in some marches. The torches are said to burn brighter in these marches. The largest torches are carried at the front, back, with three within the group. The number five is key in Hawaiian mythology. In the march of gods, there are six gods, three male, three female. The Goddess named Hi`iaka-i-ka-poli-o-Pele, (commonly shortened to Hi'iaka), is often within the march. The marches are extremely varied.