Meet my Hatchet of Death (or, some other colorful description RC Lewis and I come up with at any given moment). This is how I edit myself, it is how I edit others. If you think you want to play with me and my hatchet, shoot us an email.
We all know the first line of a query is your "hook." I call the last line the "sinker." You want it to punch them in the face, in a nice, friendly kind of way that makes them unable to forget you after having read the 300 other queries in their inbox.
If you're looking for query advice, but are slightly intimidated by my claws, blade, or just my rolling googly-eyes, check out the query critique boards over at AgentQueryConnect. This is where I got my start, with advice from people smarter than me. Don't be afraid to ask for help with the most critical first step of your writing journey - the query. My comments appear in green.
Nerine O’Shay has two goals in life. Goal one: qualify for the U.S. Olympic dive team. Goal I don't think you need to use the word "Goal" in either of these places two: finally I think the use of "finally" and "life-long" are both implying the same thing, that it's been going on for awhile. For the purposes of a query you should practice a little more word economy. However, the premise is coming across strong and it definitely has an interesting, fresh, idea persuade her father that his life-long search for the lost Spanish Galleon, the Dama de Oro, has failed. The search has cost them everything – her mother, his reputation, and now the family’s marine salvage business. Then there's the Curse that has stolen a life from her family whenever treasure is found. Nerine is convinced the next big find will kill one of them, and she'd like to actually have a life before she dies…preferably one in which fellow diver, Jason Fernandez, plays a huge part.
On the day Nerine qualifies to compete at Junior Nationals, her father finds a reef made of silver like the actually reef is made of silver? or is covered in it? If the former, what does that have to do with the ship? The wording here is a little confusing. in the waters of the Florida Keys. And there’s a lot more. Turns out the tales of the fabled Dama de Oro are true: it really was carrying a king’s ransom of gold bound for the New World. The treasure soon attracts a storm of media attention and her mother, who shows up for her share of the loot. Then the Curse strikes, sending Nerine’s carefully ordered plans into chaos, and making her realize the things money can’t buy are what she wants most.
This is a good query, overall. You've got your plot front and center, with its uniqueness in the spotlight. The one thing I would say is that if it's a straight-up contemp the idea of a Curse might raise questions about whether there's a paranormal element at work here. Other than that, clear up some word usage and phrasing in that second para and you're looking pretty good.