PROVO — Now it can be told. Terry O'Brien sank the ship at Disneyland.

If you read accounts about the opening of the park 50 years ago, you might read about how the Mark Twain paddle-wheel boat sank on one of its maiden voyages, but no details or the reason are ever given, because O'Brien didn't talk — until now.

"Now, I figure, what can they do to me? They can't fire me."

O'Brien grew up in Fullerton, Calif. He remembers as a teenager hearing about a new amusement park that was going to open. He had graduated from high school and was awaiting an LDS mission call, so he was looking for a job for a few months. He had worked at Knott's Berry Farm and enjoyed that, so he decided to try Disneyland.

"I remember going to a trailer parked in an orange grove to apply for a job." The park "went up in a hurry," he says. Two weeks before it opened, he reported for work.

It was fun to watch, he said, how all the employees "came in grubby off the streets. They'd go to the dressing rooms, and then you'd see an array of cowboys and Indians and riverboat pilots" all spiffied up.

The first two weeks they got to ride the rides and eat the food. "It was a wonderful job." On opening day, O'Brien got to meet Walt Disney and Art Linkletter, and lots and lots of other people. "They had hoped that 15,000 people might show up. But it was double that. People were lined up eight-wide to get into the park." It was a hot day, and drinking fountains were scarce. "Things really weren't quite finished. The landscaping wasn't done."

And everyone was still learning how it all worked — including O'Brien, who quickly learned that he needed to pay less attention to all the people and more attention to his job.

One of O'Brien's first assignments was to tend the "holding pen" for the Mark Twain, the area where people waited to board the boat.

"They gave me a clicker and told me to let people in until the pen was full. The boat would come in and let one group off and we'd put the other group on. No one was sure just how many people would fit, so they said to try and keep it between 200 to 300."

After a few times, it got kind of boring, so O'Brien started talking to the people and the other workers as he clicked people into the pen, not paying much attention to how many there were. The boat came in, and the next group got on.

"Pretty soon, we heard the toot-toot signal that meant disaster. And everyone wondered what had happened." What had happened was that the boat, which actually made its way around the lagoon on a rail, had sunk off the track and into the mud. There were too many people on board.