This may have been a decent "locked room" mystery, if they had simply left out the "trapped in the ballast tank" sequence. As you may have read in the goofs, ballast tanks aren't accessible from inside a sub. What is worse, though, are all the lights in the room they were in. There are lights in the ceiling, lights on the wall, even lights in the floor. This sequence really shows that Hollywood writers just don't have any new ideas anymore. Also (rambling a bit to get to 10 lines required by IMDb), the way the water rises and falls in the room is ridiculous -- slowly, like a bath tub or swimming pool. I think the poster saying the tanks are completely full whenever they are underwater is wrong, but I do believe the tanks fill and empty with water at a much greater rate. Otherwise, the sub would be stuck at the surface way too long. BTW, there is no spoiler here. The ballast tank stuff doesn't really have anything to do with the mystery of the show, especially the resolution of "how it was done."
Review of Mr. Monk Is Underwater
