Marie Friends

A scientific officer aboard US warship Abraham; he claims to be an English nobleman who's going to inherit a large wealth from his family.

The leader of the Nautilus, he and his crew battle against the Neo-Atlanteans. He is secretly Nadia's father.

Electra is an orphan since the destruction of her hometown, after which she is saved by captain Nemo and she is the First Officer of the 'Nautilus', fighting Gargoyle and the Neo-Atlanteans. Electra is deeply in love with Nemo, although she also burgeons a deep grudge from the destruction.

Grandis Granva is the head of the Grandis Gang, a trio of jewel thieves. Once a wealthy Italian noblewoman, she lost her fortune to a deceitful womanizer. She met Nadia while in pursuit of her jeweled necklace, the Blue Water. Later, they became friends.

Hanson is Grandis' henchman/friend and happens to be the brains of the Grandis Gang.

The second main protagonist of Nadia - Secret of Blue Water, Jean is a 14 year-old orphan from France who fell in love with Nadia at first sight.

King is Nadia's pet white lion cub.

Sanson is Grandis henchman/friend and happens to be the strong man, sharp-shooter, and driver of the Grandis Gang.