I had read this Death Merchant novel quite a while ago, back when I first started collecting them, but the details became fuzzy over time (sharks, ships, Nazis, etc.) so I gave it a re-read. Overall, this is a pretty interesting Death Merchant novel as almost all the action takes place at sea - there's ship to ship fighting, boarding actions, and even underwater fighting in shark-infested waters.
Long story short, a neo-Nazi organization known as Die Spinne (The Spider) has finally located the handful of survivors from a German U-boat that sank off the coast of the Falkland Islands near the end of World War Two. The submarine was carrying a fortune in Nazi gold, jewels, and other precious commodities, as well as a great many secret Nazi files that could reveal many of Germany's still-murky wartime secrets; something of even greater value than the treasure to the right organizations (remember that this takes place in 1974, only 29 years after WW2; many of the idealistic young Nazi officers in their 20's during the war would only be in their mid to late 50's, successful older men still vital enough to want to see their precious Reich rise up again).
Richard Camellion is brought in to find and "recruit" one of these survivors, and while he fails in getting one man out of Europe alive, he succeeds with another who knows where the submarine sank. Unfortunately, the Die Spinne agents also captured one of the survivors and got the location as well, so the rest of the novel is a race to see who can beat who to the treasure. Each side has at their disposal a yacht as a floating base of operations, and each side battles the other on the seas and below the waves, as well as ashore. Rosenberger did a fair amount of research into the capabilities of deep-sea divers during the 70's, including cutting-edge advances and discoveries into the sorts of exotic breathing gases (the 'diver's cocktails') needed to survive down hundreds of feet below the surface. This great attention to detail is one of the most positive hallmarks of the Death Merchant series, and goes to show that despite some of his other faults and quirks as a writer, Rosenberger has a great mind for detail and a knack for research.
I will also point out that this is the only Death Merchant novel I've read where Camellion gets laid. In order to provide a reasonable cover with regards to their pleasure yacht, several female CIA staff members are recruited and assigned to "lounge about" on the deck of the yacht, to give the impression to anyone who sails past that the ship is simply enjoying the sun and waters of the south Atlantic. Camellion beds one of the women, but the way in which he interacts with her is almost sociopathic; he seems to have little regard for her as a "real person", but not necessarily because she is a woman; more because Camellion has, in a sense, an almost autistic inability to relate to other people, and while he shares his bed with the female agent, in terms or real human closeness, the Death Merchant might as well be on Pluto.
Overall, this was a fun novel. Nazis, especially post-war neo-Nazis, are great villains to drop into any kind of PMP-style storyline, and Rosenberger makes good use of them in this adventure, particularly the ties between South America and Nazi Germany. True fact: I had a college roommate my freshman year for half a semester who was one-quarter German, three-quarters Argentinian. He as much as came right out to say his grandfather was a Nazi. Kinda creepy, actually, but cool in that surreal, pulpy, that-just-happened kinda way.