Dirk Pitt

Dirk Eric Pitt is a renowned adventurer. While Dirk may be considered the hero of the series, Al Giordino is the man behind him. In the course of his work as a marine engineer of the National Underwater and Marine Agency (NUMA), an oceanographic research organization headed by Admiral James Sandecker with Rudi Gunn as second in command, Dirk Pitt has made numerous important shipwreck discoveries, as well as thwarted a large number of plans by villains intent on global catastrophe or world domination.

Even though Pacific Vortex was published later in 1983, it is considered the 1st to be read chronologically in the series; though not required.