The sky is a deep tropical blue, rimmed with thunderheads and pierced by wind-surfing pelicans. Foliage is dense, deep green, bursting with unrepressed fecundity. It's a relief to come in out of the heat, stepping into the vast air-conditioned lobby with its tile and marble and views through broad windows...

When Shane Bauer and Josh Fattal, along with Sarah Shourd, were arrested by Iranian border guards in July 2009 while apparently just out for a hike, I'm probably not the only one who thought, "Why didn't they have a guide?"

Sure, GPS is a nice traveling companion when you're...