I haven't seen it yet and now you've spoiled the ending!
It's about the Titanic. It sinks.
AFAIK, the movie is not about the Titanic sinking, it's about the aforementioned (hemi-demi-semi)nude Kate Winslet.
-- Alphax
The movie is less about the Titanic's ill-fated voyage than about the rich man's fiancee who falls for a poor artist. It's a typical "love triangle" story. And the signature song is about the eternal, enduring love between the girl and poor Jack who sacrifices his life so that she can "go on" with hers.
The steamy scene in the car, as well as the semi-fig-leafed scene where Jack draws his new girlfriend, are not central to the movie. Even though they are real crowd-pleasers, the plot would not have suffered by editing the car scene so that the frantically-excited couple are merely shown getting into the car and doing some intense necking (leave something to the imagination). And the drawing scene would have worked just as well with PG-type fig-leafing instead of the tantalization of "Ohmygosh, is she really showing her wobbly bits?"
If we write an article on [[nudity in American film]], then the picture would be an excellent illustration. It's not really representative of Titanic, as the article stood yesterday. "King of the world" gets my vote instead.
Uncle Ed