Oddly enough I just started my summer vacation today (teacher) and have been looking for mystery adventure books myself for this summer. That said I kind of overdid it and bought a bunch mostly from Amazon . That said Ill play reviewer and tell you what I found. First, its amazing how many dive masters, dive shop owners etc. have written a self published book.
The one I already read bills itself as a dive novel but only has one dive at the end. That said, its still the one I had to read in one sitting. The guy kept my attention. Its called Out of Hells Kitchen by Dive Safety Officer John Hanzl I actually am looking for the sequel.
Next, only read a few pages of A Sword for Pizzaro by Tom Ryan, but hes a professional writer all diving and is my next to read. It definitely caught my attention.
Finally anything by Clive Cussler hes made a career of adventure dive stories and can be checked out at any library for free for 3 weeks. Little known but a really good read is Nevada Barr. Shes a retired park ranger and has two books with a lot of diving A Superior Death and Flashback a very good writer.
Flooding Hollywood and Caymen Cowboys by Eric Douglas are definitely diving but read like a report or post here on Scubaboard. Ditto with The Sea Dogs Finally Get Some Booty by Thomas Owens. To be fair Ive only skimmed these three, but they didnt jump out when I started them. All are short on dialogue and capturing me with the high adventure. A little better is Stela Passageway by Carol Kender.