Genreflecting.com defines Adventure in this way:
What Is Adventure/Suspense Fiction? Lusty spies; deadly plagues; courtroom intrigue; fanatical terrorists; murderous psychopaths; state-of-the-art
weaponry; destructive acts of nature; political conspiracies; evil Nazis; Russian crime kingpins, and international drug cartels are but a few examples of the elements that can be found in this genre. Oftentimes lumped under the catch-all label of thrillers, It is hard to precisely define adventure/suspense as authors often combine situations from other genres such as mystery, horror, science-fiction, and even romance. Although an eclectic mix, all adventure/suspense novels have a few basic commonalties.
The characters (and the reader) can always expect the worst - the main characters can,and usually do, have everything thrown at them. Action, action and more action are hallmarks of a good adventure/suspense book.
The entire read is a roller coaster ride of chills and excitement with the last stop (and page) not always ending in
happiness. And finally, there must be a villain, for without a foe…without an adversary, there can be no adventure…no suspense.
Know how I define it? Danger Zone Authors! Be sure to come for the Launch on May 11. You will meet authors who write the kind of books Genreflecting.com is talking about.