Definately start from the beginning.
Here's the list of Dirk Pitts books in order
The Mediterranean Caper (1973) Released as "MAYDAY!" in the United Kingdom.
Iceberg (1975)
Raise the Titanic! (1976)
Vixen 03 (1978)
Night Probe! (1981)
Pacific Vortex! (1983) Although Pacific Vortex was released in 1983, it is actually the first Dirk Pitt novel. The events of Pacific Vortex happen before those of The Mediterranean Caper.
Deep Six (1984)
Cyclops (1986)
Treasure (1988)
Dragon (1990)
Sahara (1992)
Inca Gold (1994)
Shock Wave (1996)
Flood Tide (1997)
Atlantis Found (1999)
Valhalla Rising (2001)
Trojan Odyssey (2003)
Black Wind (2004)
Treasure of Khan (2006)
There is also a Dirk Pitt reference book:
Clive Cussler and Dirk Pitt Revealed (1998)
Dirk Pitt Jr. adventure novels
(co-authored with Dirk Cussler)
Black Wind (2004)
The Treasure of Khan (2006)
NUMA Files adventure novels
(co-authored with Paul Kemprecos)
This series of books features Kurt Austin, head of NUMA's Special Projects division. Some characters from the Pitt novels appear such as Sandecker, Rudi Gunn, Hiram Yager and St. Julien Perlmutter. Pitt makes brief appearances in the books "Serpent", "White Death" and "Polar Shift."
Serpent (1999)
Blue Gold (2000)
Fire Ice (2002)
White Death (2003)
Lost City (2004)
Polar Shift (2005)
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