I love reading the NUMA Files series of Books written by Clive Cussler and starring Kurt Austin and Joe Zavala. As of August 2014, there are 12 books in the series. Below are all the books each with a brief review and my own opinion.
Kurt Austin is Head of the US National Underwater and Marine Agency's (NUMA) Special Assignments Team. He took over the position from Dirk Pitt, after Admiral Sandecker was elected Vice President of the USA, and Dirk Pitt was promoted to take over the Admirals job as Director of the NUMA agency. That gives us some continuity, but also a whole different series of adventures. There are actually four people on Kurt's team, but the other two have not been fleshed out as real characters as much as I would like them to be, so I'm going to ignore them for now.