Yemaja is an orisha, originally of the Yoruba religion, who has become prominent in many Afro-American religions. Africans from what is now called Yorubaland brought Yemaya and a host of other deities/energy forces in nature with them when they were brought to the shores of the Americas as captives. She is the ocean, the essence of motherhood, and a protector of children.
The goddess is known as Yemanjá or Iemanjá in Brazil.
Every February 2 in Salvador, Bahia, there is a celebration of Iemanjá, which involves thousands of people lining up at dawn to leave their offerings at her shrine in Rio Vermelho. Presents for Iemanjá usually include flowers, perfume, and objects of female vanity (jewelry, combs, mirrors). These are gathered in large baskets and taken out to the sea by local fishermen. Afterwards a massive street party ensues.
In Rio de Janeiro, Iemanjá is celebrated on New Year's Eve, when millions of cariocas dressed in white gather on Copacabana beach to greet the New Year, watch fireworks, and throw flowers and other offerings into the sea for the goddess in the hopes that she will grant them their requests for the coming year. Paintings of Iemanjá are for sale in Rio shops, next to painting of Jesus etc. They portray her as a woman rising out of the sea. Small offerings of flowers and floating candles are left in the sea on many nights at Copacabana.