I've enjoyed seeing the movie, Master and Commander, with Russell Crowe, every time, so the book should be interesting and gets some good reviews... Patrick O'Brien.
Also movie based with reviews that the book's even better... Mutiny on the Bounty, Nordhoff and Hall.
And another movie which should provide good reading... Treasure of the Sierra Madre with Humphrey Bogart... written by Traven.
Some of the adventure fiction stuff is downright trashy, and maybe Stephen King falls into this camp.... maybe The Shining, more along the lines of horror.
Science fiction, Contact by Carl Sagan. Not adventure, but it is fiction and a universe away from the reality outside the tent. Also 2001 A Space Odyssey, Arthur C. Clarke, and the sequel book, 2010.
I've read Norman Mailer's The Naked and the Dead several times now, fictionalized history about a WWII American invasion of a Japanese-held south Pacific island and will probably read it again, there's something about it. Goes slow but believable and engaging, drawing you in to the misery and reality of war but not a lot of adventure in it.
Hawaii, Michener... a long read, if you've got rainy days inside the tent.
Maybe Shogun, James Clavell... another long read for rainy days and long nights and filled with Japanese details. Not too big on adventure but does have it's moments.