What sort of shows were these that you worked on as a technical diver? Is this a Seaworld-type of situation? But not sure why they would need underwater lifts.
Here's a video during construction: https://www.youtube.com/watch?v=35WJDSoA8Ag&t=13s
And you can check YouTube out for more of the motorcycle act, Russian Swings, high-dive, and other acts.