3. No Wetsuit for Kate Winslet
Kate Winslet was one of the few actors who didn't want to wear a wetsuit during the water scenes.
Although in the scenes after the boat sunk, the actors were in warm water, in the scene where Rose goes looking through the corridors of the sinking ship for Jack, the water used in the scene was from the Pacific Ocean.
The water was so cold that when Rose gasps upon diving into the water, it was the actress’s genuine reaction to the frigid ocean water.
As a result of not wearing a wetsuit in the cold water, she got pneumonia.