Here's the picture of what happened to seaQuest that I have built over the years after going to numerous forums, reading stuff about seaQuest, and getting my hands on 2 of the 3 tie-in novels.
seaQuest was initially going to be about the reunification of a post-WWIII world and building a stable peace (this is based on the televised pilot, it's novel, and the second sQ novel) by having seaQuest going around stopping undersea pirates and doing other stuff. Then Spielberg came around and decided to make it more like 20,000 Leagues Under the Sea, which caused one of the producers who was in favor of the post-WWIII stuff to quit. The pilot and novels retained these elements due to being the earliest productions (most early tie-in novels for shows are based off the show bibles instead of the shows themselves in order to get them on shelves in time to cash in on the show). Season one ends up being TNG underwater, with some elements of the original idea cropping up here and there, but never really meshing properly. The show is pretty light on action and NBC has the writers put in an episode where the crew meets legit aliens late in season 1 to spice things up. It does well enough to get renewed, but production moves to Florida because it's cheaper than filming in Malibu. Bob Ballard decides to stop doing his little end credits bits sometime between the end of season 1 and the beginning of season 2 because the show is moving away from legit science to the usual scifi nonscience. Spielberg is long gone at this point, off doing movie stuff and getting memos on cartoons he's producing (such as Tiny Toons and Animaniacs).
Season 2 starts off pretty well with Daggers, a story about genetically engineered super soldiers taking over the prison they are in, which has a good mix of action and plot. However, the writers have a mandate to make things more "scifi" or something, so they come up with ridiculous drivel that smacks of post-season 1 Voyage to the Bottom of the Sea, with occasional good works like The Sincerest Form of Flattery (an episode where the seaQuest crew has to face off with an AI sub controlled by an old copy of their captain's mind) and Daggers Redux (where the ring leader of the Dagger prison revolt is given a sub to sink seaQuest). The worst part of season 2 is that there's an arc revolving around more aliens, which leads to the season finale where seaQuest is apparently sunk. Roy Scheider, who plays the captain, decides to quit when the show is renewed because of how terrible the writing is and NBC fires a few cast members in order to make the show cheaper, along with getting an entirely new theme to save money on that too.
Michael Ironside comes along and manages to leverage himself into a producer position, then suggests the bleeding obvious, having a military based arc for a show set on a submarine. They set season 3 ten years after the end of season 2 and back on Earth, where things devolved into a cold war after seaQuest disappeared. The writers put out some decent mil scifi, with the occasional stumbles (such as an episode where seaQuest travels back in time to the Cuban Missile Crisis), but NBC decides to preempt them constantly and cancels them after the 13th episode is produced and a new antagonist is introduced in said episode.
And sadly, the seaQuest DSV concept has been left to rot for nearly 20 years, while tons of other stuff have gotten remakes and reboots. All this because Steven Spielberg dropped an idea that had no long term viability and was probably implemented solely because none of the writers and producers had the balls to say it was dumb.
