Cau Ngu festival originates from the worship of Mr. Nam Hai, a whale with a large body but a peaceful nature, often helping fishermen when they encounter distress at sea. The long-standing custom of the inhabitants of the sea from Quang Binh onwards (in which the most typical is the South Central region). Mr. Nam Hai Ngu is also known as the Duc Ong, Ca Ong or Ong Nam Hai fish from the southern provinces.
When Mr. Ong's fish died, drifted ashore in the territory of a sea village, the sea villageers had to hold a funeral and set up a shrine to worship the fish.
The festival is meant to worship the Whale (Mr. Nam Hai), praying for a good harvest season, calm waves, and safety for all sailors. Fishermen believe that in addition to having extraordinary power, Ca Ong is also capable of understanding their will, always helping the sailors through hardship.
Festivities start from dawn with the Nghinh Ong ritual, the main and most important etiquette. The ceremony was carried out basically to receive Mr. Nam Hai's spirit from the sea to a place of worship.The boat during Nghinh Ong's move from the fishing port to the seaport is to perform the ritual that lasts around 2 hours. The boats are decorated with colorful flags, including Le Chinh boat, Ba Trao boat, Lan boat.
After the offering ceremony, Mr. Nam Hai returns to the Dinh ceremony. The boat team returns to the the fishing port under the bright sun with the jubilant welcome of the Cua Be fishing village people. Ba Trao team will sing "Phung nghinh Hoi Dinh" on the whole journey to receive him to Truong Dong communal house.
From the past, the procession he always held solemnly, close, sacred and considered a great festival for the people of the sea. Besides, traditional classical opera singing is also one of the most anticipated events.
The festival continues for two days afterward with various family rituals and folk games, attracting many locals and neighbors to join.