Beach-style pancake
People can dive for sport and entertainment, but for other people, it’s how they make a living. Or, in this person’s case, diving is how they earned extra scratch on the side. This person part-timed as a boat cleaner whose job was to scrape the undersides of boats.
While working, the OP was scared witless when they saw the boat move lower and lower. The OP was stuck between a boat and a hard place, and if they didn’t move, they would’ve become a pancake that day. Luckily, they were able to get out of harm’s way in the nick of time.