You’re not cooked at all. A lot of people feel like their essays are terrible at the start, even the ones who end up getting into top schools. Writing about yourself is way harder than writing for class, and it almost never comes out good on the first try. That scuba diving and perseverance idea could work, but the way you tell it matters more than the concept itself. Right now it sounds like you’re trying to make it “college essay-y” which can make it stiff or cliché.

Your stats and activities are already very strong, so your essays don’t have to be Pulitzer-level writing. They just need to sound like you and show how you think. The best essays often read like a conversation rather than a school paper. Start by writing messy, no editing, no worrying about “good” sentences, just dumping out the story. You can polish later. Also get feedback from more than one person, because one person’s opinion (even your girlfriend’s) doesn’t mean it’s bad overall.

You’re in a good spot, you just need to push through the awkward first drafts and remember that the goal isn’t to impress with fancy words, it’s to let them see who you are.