In the book Science Fiction Television Series, Liam Sullivan recalled filming his giant underwater scenes in a 12-foot tank of water. After the third take, he was supposed to jump up, catch a wire stretched over the tank, and pull himself up. He missed the wire and fell back, completely out of breath. Two divers leaped in and pulled him up before he drowned. Three weeks later, Irwin Allen decided Sullivan's make-up wasn't scary enough, and they did it again. According to the Irwin Allen book, Sullivan insisted on having the tank half drained, so that he could get air more easily.