I'm gonna lose my mind if I don't find this novel from the mid 2000's about a kid and his friends on a deep sea adventure.

All I can remember is that the cover had the main kid (a guy with blonde hair I think) and his friends in a submersible of some sort. The cover was illustrated and was mostly dark blue and had orange light shining out in to the water from the cabin of the submersible where the kid (or kids maybe) were sitting. I remember he reunited with his father at the end of the book (or I'm hallucinating)

That said- I enjoyed this book and read it around 2006-2008 and I believe it was a new novel at that point. I've been trying to remember it for a decade and have failed in my exhaustive search for it.