I had never heard of a "bed bus" until I boarded one bound for Poipet, a small city on Cambodia's border with Thailand. After squeezing down an aisle that thin people have to walk sideways to fit through—two tiers of beds down each side—I soon discovered that the bunks were double-occupancy, meaning I had to share the last remaining 3.5-foot-wide by 5-foot-long bunk, all the way in the back of the bus, with another person for the 9-hour ride through the dark, bumpy night.

A sign should be posted, I thought, that warns those fearful of heights not to enter. I was walking into a riverfront slum, one in which every home was built on stilts—some very high stilts. Even the sidewalks that weaved through this collision of cobbled-together buildings were built on interconnected stilts that tied everything together in what seemed an uneasy truce with gravity. I didn't want to look down, as it was impossible to avoid seeing the ground far below through the gaping gaps between boards—but if I didn't, a slight misstep might seriously ruin my day!