It's interesting that ILM went with a smoke chamber to shoot the underwater scenes in this film. It was probably a lot easier than shooting underwater and less likely to screw up the models. Some of the time this method looks fantastic but, at other times, it looks like a model in a room full of smoke. I've always found the underwater model scenes shot for Das Boot[1] to be more convincing.

[1]https://theasc.com/articles/das-boot

It's less about screwing up the models as much as not needing a pool, as well as not needing underwater capable cameras. Underwater rigging for cameras puts incredible limitations on what camera is used, the motion of the camera, etc. Keeping everything dry is always going to be preferred. The motion control equipment isn't meant for use underwater either. It just makes much more sense to shoot it dry. Especially considering this was before CGI and 3D rendering was in its infancy, maybe toddler stages.

Underwater scenes on "For your eyes only" (1981) were all filmed on land because Carole Bouquet couldn't go underwater. When you know it you can see it, but when I saw the film (one of the first time I ever went to the movies) I didn't notice it at all.

Adhesion and cohesion always fuck up scenes that combine scale models and water. Splashes always look very wrong, and in the case of a submersible bubbles could be a problem. Smoke chamber makes sense.

Although in the days since “O Brother Where Art Thou?”, when they added dust-yellow color to the entire movie in post, maybe there are other ways now, if you didn’t want to go entirely to CGI.