the whole movie was an excuse for cameron to go to the titanic. however he went in a craft designed and tested for this purpose that wasnt a deathtrap.

In an interview for Playboy, James Cameron stated, “I made ‘Titanic’ because I wanted to dive to the shipwreck, not because I particularly wanted to make the movie.” After realizing that diving to see the sunken Titanic was an actual possibility, Cameron began thinking up how he might be able to fund a trip down to the ocean floor to see the ghost ship for himself. “When I learned some other guys had dived to the Titanic to make an IMAX movie, I said, ‘I’ll make a Hollywood movie to pay for an expedition and do the same thing,’” he told Playboy.

https://www.slashfilm.com/839799/the-most-influential-vfx-artists-in-movie-history/