The Osun-Osogbo festival, without a doubt, is more than just sacrifices performed to celebrate the Osun River goddess.Not anymore, at least. There are several activities planned around the festival, as tourists and visitors all come to witness, interact and partake in the two-week long celebration held in Nigeria
However, there is a sequence of rituals that kicks off the celebrations and they are:
1. The Iwopopo Ritual: This is a ritual done to cleanse the city from evil. It is done first before the festival starts properly.
2. The Ina Olujumerindinlogun Ritual: This is the traditional ritual that involves the lighting of a 16-point lamp which is believed to be 600 years old. This ritual is carried out three days after the Iwopopo ritual is done.
3. The Iboriade Ritual: The Iboriade ritual is when all the crowns of the past kings - Ataojas - are assembled for
blessings by the sitting Ataoja of Osogbo, the Arugba, the Yeye Osun, and a committee of priestesses.
4. The Arugba Ritual: This is one of the major highlights of the festival. A calabash containing the sacrifice materials that
would be used to appease and worship the goddess is carried across town by a votary virgin, on her head. As she leads the
procession to the river, the people, seeing her as a representative of the goddess, cast their problems on her and say prayers.
Via Source: https://religiousbroadcast.blogspot.com.ng/2017/08/osun-sacred-groove-in-worship-of-river.html?m=0