Patagonia makes a pretty good shoulder bag called the "Vertical Mass." I use it for traveling, along with their Maximum Legal Carry-on. It's great for carrying everything you need exploring: SAK, first-aid kit, lunch, water bottle, wind breaker, maps, guide books, passport... I used it last year traveling in Mexico and South America. Best thing is to avoid carrying anything that looks "tactical" and have the army/police mistake you for a criminal or revolutionary.

My $0.02