Dean King so wants to have a bromance with his favorite author Patrick O'Brian. Hey, who am I to talk, I popped an O'Brian boner too when I walked into a bookstore and found upon a shelf
Harbor and High Seas: An Atlas and Geographical Guide to the Complete Aubrey-Maturin Novels of Patrick O'Brian.
O'Brian's 20 book series (21 if you count the unfinished one) can be read and enjoyed without such Cliffs Notes-style assistance. However, O'Brian wrote with exquisite attention to detail for time and place, so if you've read this seafaring epic set in the early 1800s and are left with as many questions as I was (what the hell is a backstay and where is Minorca?), you'll find King's work admirably fills in the gaps pertaining to setting with illustrations and maps. And since Captain Jack Aubrey and his surgeon-friend Stephen Maturin find themselves on the far sides of the world in ports and upon coasts foreign to most readers and no longer existent in some cases, understanding the lay of the land can only further enhance your enjoyment of landscapes so intrinsically tied to the story.
NOTE: I would not suggest reading this book before reading O'Brian's works, as
Harbors and High Seas is filled with spoilers. But each chapter deals solely with one book, so you can read a book and then read a chapter, and get the "ahhhh" of understanding I didn't get until I found this very helpful book.