Infiltration of the Secret Base
Marie and King are captured by the soldiers, so Jean and Nadia set off to a forbidding looking area to save them. Their rescue mission leads the pair to the base of the soldiers, who call themselves Neo-Atlantis, and their evil commander, Gargoyle, wants Nadia and her Blue Water at all costs.
Aired 18/05/1990EP 6 - Infiltration of the Secret Base

Nadia: The Secret of Blue Water
In 1889, the world is on the pinnacle of great discoveries in technology. In mankind's grasp for the future, a sinister foe known only as Gargoyle, obsessed with restoring the former Atlantean empire to the glory it once held, begins his plans to take over the world. Nadia, with the help of a young inventor, Jean Raltique, and the mysterious captain Nemo of the submarine Nautilus, must fight to save the world from Gargoyle and Neo-Atlantis. Based on the Novel '20,000 Leagues Under the Sea' by Jules Verne.
(Source: Anime News Network)