Nadia: The Deep Blue Sea is the sixth volume in ADV's DVD release of this classic series. Containing four episodes, Deep Blue Sea makes a dramatic turn from the shipboard stories, as Nadia, Jean, Marie and King are once again on their own.

Artwork and animation is on par with the standard set by previous volumes. The mecha fans should have a field day with the well-detailed battle scenes between the Garfish and the Nautilus. A lot of attention is paid towards size and scale established by these machines. The artwork also goes a long way to help the dark mood of these episodes.

Acting for both voice casts stays in rhythm with the serious tone. The whole cast gets a bit of a stretch as each explores the emotions of the big revelations found in the second episode. Focus comes back to the children, giving plenty of time for the actors to express a wide range of emotions. Of course Marie and King remain as jovial as ever, so there is only minor expansions in these portrayals.

Nadia, originally planned for 26 episodes, was popular enough to stretch the series to 39. Much of the expansion came in the form of an Island story arc that our heroes find themselves in. These episodes step away from the jovial nature of many of the previous episodes as serious revelations come to light. Electra, Jean and Nadia are most changed by what occurs in these episodes. Each character grows a bit as secrets about Nemo's past and the true nature of the war against the Neo Atlantians comes to light.

For Jean and Nadia, the most changes come during their separation from the Nautilus. Marooned on an Island, Nadia turns her back on all things science. This effectively drives a wall between her and Jean as he struggles to be true to his nature. While overly dramatic in nature, comic moments still pop up (such as Marie playing a popular word game with King).

Deep Blue Sea truly is a turning point for Nadia. The biggest secret this series had is now out in the open, changing everything. Nadia effectively goes to an extreme to avoid the truth just revealed. The comic moments and touching scenes that have punctuated this series take a step back allowing the full drama of these events to unfold. Despite beginning a series of filler episodes, the series has taken a huge step towards its conclusion.