This is an episode list for the American adult animated television series Sealab 2021. Cartoon Network aired the show's first three episodes in December 2000, with the remaining episodes airing on Adult Swim from September 2, 2001, to April 24, 2005. 52 episodes and four seasons in total were produced.
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An untitled pitch pilot for the series was produced, and while never aired on television, it was later released on the Season 1 DVD.
Prior to the creation of the Adult Swim programming block, three episodes aired at various early morning times on Cartoon Network.