Underwater shooting in an abandoned nuclear power plant and a lake in Missouri drove the actors close to desperation.
Until 2007, the full-scale set for Deepcore was still intact at the filming location:
Here's a video about building the sets (this is Part 1):
Fortunately, given all the agony and risk that went into this edgy project, the director's cut has aged well.
I regard one scene as a remarkably vivid depiction of what a massive system failure feels like for those trapped on the inside. It's a segment in which a massive crane collapses into a moonpool on the Benthic Explorer, and then plummets toward the Deepcore rig, setting off a harrowing chain of events. I've never seen a movie that captured this techno-suspense as well as Abyss. (I'm not a big fan of the last twenty minutes of the film, but the earlier part makes up for it.)
As Shakespeare wrote in Hamlet, sorrows come in battalions rather than single spies, and this part of the movie captures the feeling of utter helplessness as machinery spins out of control.
As I mentioned in this post on the history of underwater exploration, during the 1970s offshore oil companies considered putting manned, underwater drill rigs on the deep ocean bottom, along the line of Deepcore, but in the end they opted for the conventional approach of leaving the wellheads at the mud line, and the drilling rigs on the surface, connected by a riser pipe.
And it was a smart choice: since then, remotely-operated submersibles have proven to be the best method for carrying out work that's more than a few hundred feet of depth. There's a lot of work for ROVs to do in the deeps of the Gulf of Mexico, off Brazil, off West Africa, and other spots, particularly after production starts. Much of the production hardware -- valve trees, pipes, pumps -- runs along the seafloor, more than two miles down, and only ROVs can handle that kind of maintenance.