The first 23 novels in the Dirk Pitt series in chronological order: 

1. Pacific Vortex

2. The Mediterranean Caper

3. Iceberg

4. Raise the Titanic

5. Vixen 03

6. Night Probe

7. Deep Six

8. Cyclops

9. Treasure

10. Dragon

11. Sahara

12. Inca Gold

13. Shock Wave

14. Flood Tide

15. Atlantis Found

16. Valhalla Rising

17. Trojan Odyssey

18. Black Wind

19. Treasure of Khan

20. Arctic Drift 

21. Crescent Dawn 

22. Poseidon's Arrow 

23. Havana Storm

The picture is just an example. Actual books you get may have different covers. 

Check out our other Clive Cussler lots.