I’ve seen both the 1972 with Shelly Winters and the 1990s version of “The Poseidon Adventure” with Fergie Ferg, neither of which were spectacular examples of cinema, but were fun. The first one, Shelly Winters is an overweight, rich lady (I think) who finds purpose in the upside-down-ship, partially submerged in water, because she connects with her swimmer past and feels purpose, assisting the others. She says something like “in the water, I’m light as a feather.” I think she says again it before she dies too.
But for me in the second grade, the most impressive part was the upside-down ship, so that all the surviving guests had to traverse a flipped-over landscape — the ceiling was now the floor. It was curved, had light fixtures, etc. I don’t know if it was like my emergency preparedness instinct, but I used to spend hours walking through my parents’ apartment with a large mirror, making sure I knew where I’d be walking just in case I ever had to walk on the ceiling.