I use a pretty simple plan when in ports... (any port)... I don't wear anything that can be "yanked" off (like a necklace)...
I use my Samsonite (cut proof) travel bag worn across the body.
(it is lockable....so no worries about pick pockets)
If we go to a beach, I don't get in the water (or in the sun for that matter)...so I "guard the stuff" in the closest shade area.