Large Capacity Men's Waterproof Backpack - Single Shoulder & Crossbody Style - Multi-Pocket Design for Business & Casual

A good full length zip area for your special belongings. 

Do  not trust travel sling over the shoulder bags with no zips as they are easy for light fingers to slide into as there is no protection for the pockets as you are walking along.

 I have seen some where it is obvious the belongings may even fall out of their own accord.

At the front, a place to attach your keys so that they are not lost. You could actually attach them and then roll them into the extra 6" front zipped security pocket. 

Next to the security pocket at the front is a place for your mobile phone or a card wallet, though I would prefer mine inside the big zipped compartment, but you may think otherwise.

Good as an aircraft bag to take permissible items onto the plane.

Don't want to trust the hotel security, wear the bag under your coat or suit jacket, strap to your chest under your jacket coat and easily reach in for what you need, much safer place for your valuable documents and cards, even a ring for your key fobs.

Cards ? - Under the front pocket for lightening fast access or zipped away for extra security inside a card keeper.

Don't take risks abroad or even in this country.