In titanic how did cal die?

Cal Hockley, played by Billy Zane in the movie "Titanic," doesn't die in the film.

He survives the sinking by boarding a lifeboat. He leaves Rose DeWitt Bukater (Kate Winslet) behind, refusing to share his lifeboat seat with her. The last scene of the film shows Cal decades later as an old man, clearly haunted by the events of the night the Titanic sank.