Yemoja is a major water deity from the Yoruba religion. She is an orisha, in this case patron spirit of the oceans and/or rivers – particularly the Ogun River in Nigeria. She is often syncretized with either Our Lady of Regla in the Afro-Cuban diaspora or various other Virgin Mary figures of the Catholic Church, a practice that emerged during the era of the Trans-Atlantic slave trade. Yemoja is motherly and strongly protective. She cares deeply for all her children, comforting them and cleansing them of sorrow. She is said to be able to cure infertility in women. Cowrie shells represent her wealth. She does not easily lose her temper, but when angered she can be quite destructive and violent, as the flood waters of turbulent rivers.
Yemoja is often depicted as a mermaid. She is associated with the moon (in some Diaspora communities), water, and feminine mysteries. She is the protector of women. She governs everything pertaining to women; particularly the birth and bearing of children – childbirth, conception, parenting, child safety, love, and healing. According to myth, when her waters broke, it caused a great flood creating rivers and streams and the first mortal humans were created from her womb.
In traditional Yoruba culture and spirituality, Yemọja is a mother spirit; patron spirit of women, especially pregnant women; She is the patron deity of the Ogun river (Odò Ògùn) but she has other rivers that are dedicated to her throughout Yorùbáland. In addition, she is also worshipped at almost any stream, creek, springs in addition to wells and run-offs.
Her name is a contraction of the Yoruba words Iye, meaning “mother”; ọmọ, meaning “child”; and ẹja, meaning “fish”; roughly translated the term means “mother of fish children.” This represents the vastness of her motherhood, her fecundity, and her reign over all living things.
In West Africa, Yemoja is worshipped as a high-ranking river deity, but in Brazil and Cuba she is worshipped mainly as a sea/ocean goddess. River deities in Yorubaland include Yemo̩ja, Ọ̀ṣun (Oshun), Erinlè̩, Ọbà, Yewa, etc. It is Olókun that fills the role of sea deity in Yorubaland, while Yemoja is a leader of the other river deities.
The river deity Yemoja is often portrayed as a mermaid, even in West Africa, and she can visit all other bodies of water, including lakes, lagoons, and the sea, but her home and the realm she owns are the rivers and streams, especially the Ogun River in Nigeria.
Additional source: Wikipedia