The mini-sub is launched- in The Abyss (1989)
James Cameron's The Abyss is one of my all time favorite effect movies. It uses every technique under the sun, which is why it works so well. I could have picked any one of the hundreds of amazing shots, but I've chosen an obscure, throwaway shot, most people will barely notice.
When a shot was needed to show the Cab Three mini-submarine launching from the deck of the Benthic Explorer, the filmmakers had just one little problem: Benthic Explorer didn't exist. To work around this, they used the ancient forced perspective technique.
A miniature quarter scale launch well, complete with tiny bumpers, was suspended above the studio floor. The extras and the railing were 10 feet below the water, but because the camera only sees in two dimensions, they look like they are well above it. To get the proper scale the shot was completed as two in-camera passes: First the miniature sub was dropped in the tank, shot at high speed, with the rest of the set blocked off. Then the film was rewound and the extras were shot on the full-scale set, while the miniature tank was in darkness, effectively serving as a matte for the already exposed part of the image.
The end result is flawless. Pure movie magic.