"Walden" by Henry David Thoreau
An adventure book doesn't need to feature swashbuckling badasses climbing mountains or sailing the rough seas. It doesn't even have to offer up much action at all. Such is the case with Henry David Thoreau's Walden. It's a book that, while glacial in its pace compared to a few of the titles on this list, is one man's adventure of going it alone in the woods of Massachusetts.
The idea of a person giving it all up so he can drop out for awhile to just explore nature, be by himself, and survive on mostly his wits, just doesn't seem likely in our hyper-connected world. Somebody doing it and writing so clearly and beautifully about it seems downright impossible. That's what makes this timeless. [$6, amazon.com]