The third dimension is terror
Released: July 22, 1983
Thanks to a faulty gate, a great white shark swims into Sea World of Florida. Ignore the fact that Sea World is located in Orlando, a good hour's drive from the ocean. Anyhow, Mike Brody just happens to work at Sea World as an engineer, along with his girlfriend, Kathryn, a marine biologist who plays with whales all day. It also just happens that Mike's brother Sean, now college aged, comes for a visit just as the park is nearing its grand opening.
Dinner Time
Night falls and one of the workers goes diving in order to fix the gate. He hears a funny noise once, it's nothing, twice, it's nothing, three times, he gets eaten. In the theatrical version, there was a really cool shot of his severed arm floating around in 3-D. Meanwhile, Mike and Kathryn have taken Sean out to party and he meets a Sea World waterskiier named Kelli. She helps him overcome his aquaphobia by making out with him in the Sea World lagoon. While they're doing that, some blundering thieves show up with the intention of stealing coral from the lagoon's bottom. The shark first eats the guy who dives for it, then pulls his amigo in and gets him too. Then the shark pops their raft. Just for the Hell of it, I guess.
The next day, Mike and Kathryn learn of their co-worker Overman's disappearance and they tool around in one of those nifty submersibles looking for his waterlogged corpse (they assume he drowned). By the way, the effects here are so bad. So bad. Kathryn's dolphins follow them around when they leave the submersible, and a couple minutes later the shark appears. Funny thing is, he seems more interested in the dolphins than the humans. The mammals lead Mike and Kathryn to safety, and escape the shark as well. Phillip FitzRoyce, a snooty British adventurer who happens to be visiting the park, declares that the beast should be killed on live TV. But the ghetto-talkin' park owner, Calvin Bouchard, decides to have the thing captured so they can put it on display. So we watch as the shark is drugged and put in a tank. Opening Day arrives, and all seems well. Then the shark gets sick and dies.
Don't you hate when this
happens? 
The mutilated corpse of Shelby Overman is found and it becomes obvious that he was killed by an X-LARGE shark, not the one they caught. Mike and Kathryn decide that the dead shark's mother is also in the park, and since it's Opening Day, it should be showing up real soon. And it does, chasing the ski teams and what not. It's a damned fast shark. When it gets tired of chasing the skiers, the shark tips over the bumper boat of......yes, you guessed it, Sean and Kelli. Kelli is bitten on the leg, and even though the shark is the size of a freakin' Suburban, she just gets a little gash when she should have lost her leg. Kelli actually survives. The shark gets bored again, and this time attacks the underwater observation tunnel, which is packed with screaming, overacting extras. The tunnels fill with water, and the extras get trapped.
People who never acted before and
haven't acted since
So Mike has to make a patch for the tunnel and don scuba gear in order to fix the leak so the extras don't drown. FitzRoyce lures the shark into a filtration pipe, but ends up in the shark's mouth. He doesn't get eaten, he's just stuck in the shark's mouth and apparently suffocates. The shark bashes her way out of the pipe and goes after Mike. Luckily, Kathryn and the dolphins have come along and they help Mike get away. The couple seeks refuge in a decompression tank, but the shark uses her teeth to keep the door from shutting. They finally escape and the water is drained out of the tunnel and the extras go home.
But there has got to be at least one cheezy 3-D technique left. Mike and Kathryn and the others are in the underwater control room when they spot the shark swimming in slo-mo towards the glass window.
It's called Plexiglas, people 
Everyone does a slo-mo "NOOOOOO!" and the shark smashes through the glass, an effect that might've looked cool on the big screen. Calvin and some broad without a name escape somehow, but the shark gnaws on the kindly black control room attendant, Redd by name. This is the first time Jaws ever takes dark meat. Mike and Kathryn survive by putting their scuba gear back on, and they notice FitzRoyce's corpse lodged in the shark's yap. He just happens to be holding a convenient grenade in his hand. Mike uses a pipe or something to pull the pin, and he and his woman take shelter as the beast explodes.
It's a wonder they survived--according to my dad, their brains would've hemorrhaged during that underwater explosion they were all of five feet away from. Anyway, they go to the surface and all Kathryn cares about is if the dolphins lived. After a few seconds of nail-biting suspense, we find out that they did! Oh, what a happy ending.
Ignore the huge lawsuit that
would've been brought by the tourists in the tunnels, which
probably would shut the park down.