Producer Irwin Allen’s feat of special effects launched the ’70s disaster movie cycle with a splash: a cruise liner is capsized by a tidal wave, plunging its passengers into “Hell Upside Down” per the tag line. Muscular Christian priest Gene Hackman leads a group of survivors (including Shelley Winters, Ernest Borgnine, and Stella Stevens) upwards towards the engine room as the waters rise behind them. Who will survive?