The Abzu (Cuneiform: , ZU.AB; Sumerian: abzu; Akkadian: apsû, ) also called engur, (Cuneiform:, LAGAB×HAL; Sumerian: engur; Akkadian: engurru) literally, ab='ocean' zu='deep', was the name for the primeval sea below the void space of the underworld (Kur) and the earth (Ma) above. It may also refer to fresh water from underground aquifers that was given a religious fertilizing quality. Lakes, springs, rivers, wells, and other sources of fresh water were thought to draw their water from the abzu.

Abzu, Abžu, or Abzû may refer to:

• Abzu, also called engur, ancient Mesopotamiam name for the primeval sea below the void space of the underworld
• Abzu (video game), diving simulator
• Abžu dialect, Abkhaz language
• Abzu (album), by black metal band, Absu