Cameron is not known for his kindness on set.
Much of Cameron’s 1989 film “The Abyss” takes place underwater. One scene had actor Ed Harris taking a long underwater swim of over forty feet, without any source of oxygen. According to “The Futurist: The Life and Times of James Cameron” by Rebecca Keegan, safety crew, or ‘angels,’ had to stay far enough away to not get caught on camera, so when Harris made the “out of air” gesture, it took a while for them to get over there with O2 tanks. It left Harris and the other actors exhausted, but there were no incidents—not until another scene where Harris had to hold his breath in a water-logged helmet.
When Harris gestured for help, it didn’t come because his personal angel had been caught up on ropes. Another angel swam over, popped open his faceplate and put a regulator in his mouth—only it was upside down, so Harris took in a gulps of water and later said he thought he was going to die. During a press circuit, he likened his experience on set of “The Abyss” to a Vietnam soldier. His co-star, Mary Elizabeth Mastrantonio, reportedly said "‘The Abyss’ was a lot of things. Fun to make was not one of them."
So the lesson here is not to work with James Cameron if the project requires going underwater. There’s probably a reason why he took the Deepsea Challenger alone.