Nadia: The Secret of Blue Water (Japanese: ふしぎの海のナディア Fushigi no Umi no Nadia, Nadia of the Mysterious Seas) is a famous Gainax series very loosely based on various Jules Verne novels, particularly Twenty Thousand Leagues Under the Sea and the exploits of Captain Nemo. The series was chiefly directed by Hideaki Anno, director of other famous Gainax productions such as "Neon Genesis Evangelion," "His and Her Circumstances," and "Top o Nerae! GunBuster," with character designs by Yoshiyuki Sadamoto and music by Shiro Sagisu. (Gainax co-founder Shinji Higuchi served as director from Episode 23 onward.)

The lead characters are an orphaned young inventor named Jean, who lives with his aunt and uncle, and a dark-skinned former circus performer named Nadia, who wishes to return to her home in Africa. Many of the designs in the series, including characters' appearances and several machines, showed up in later Gainax works. In particular, several characters in Neon Genesis Evangelion vaguely resemble Nadia characters due to the same head design artist, Yoshiyuki Sadamoto, working on both. Sadamoto has said that the design of Shinji Ikari, the protagonist of "Evangelion," is basically the result of giving Nadia a "masculine makeover."

About two-thirds into its run, the production ran into financial difficultes, since the series was a huge hit and NHK wanted more episodes than had been originally planned. It had to be budgeted to cheaper overseas animation, resulting in a noticeably sharp decline of animation quality and an odd shift in the use of sight gags. (Many consider this the first example of Gainax's tendency to go way over budget during the early stages of producing a TV series and end up having to finish the series on a shoestring; other notorious examples can be seen in Evangelion and His and Her Circumstances (Kare Kano). Gainax has never made another series as long as Nadia; both Eva and Kare Kano ran for 26 episodes.) A less famous movie, "The Secret of Fuzzy", was released in 1993, but generally regarded as poorly plotted and animated, with no involvement from Anno or Gainax outside of some flashback footage from the TV series. It was not received favorably and is almost unheard of by most American fans of the series.

In its original Japanese broadcast, it aired from 1990 to 1991 and ran for 39 episodes. The complete television series and aforementioned movie are currently available in the United States from ADV Films on DVD. ADV's Anime Network has broadcast the series in the United States. Reportedly, the series was to have been screened on TV in the United Kingdom in the mid-1990s, but the U.K. distributor balked because of the amount of violence in the series (which is never gratuitous but is at a greater level than most English-speaking viewers might be used to in TV animation). In Italy, the series was shown on TV as Il mistero della pietra azzura, and it has also been screened in France as Nadia, le secret de l'eau bleue.

- From Wikipedia