Where better to 'start' than at the end. Carl Brashear(played here by Cuba Gooding Jr) taking the twelve required steps to prove he was still capable of doing his job...unassisted...in a heavier suit...with ONE functioning leg.
The racist camp commander didn't want Carl to pass the final exam, which involves assembling a portion of piping underwater. When they send the bag of parts down to him, they intentionally cut the bag open, sending the tiny pieces scattered across the bottom. Dismayed, Carl gives up. Nah, just kidding. He spends the next nine hours in freezing water assembling the pipe. He's shivering, practically blue, and barely conscious when he emerges, but he does it. Determinator doesn't begin to describe.