Night train Colombo to Badulla with big backpacks — cable lock enough or is luggage theft still common?

Theft is not guaranteed, but overnight trains and buses reward basic paranoia. Cable-lock bags to the rack, keep passports/electronics on your body or as a pillow, use a light packable lock on zippers, and take turns dozing if you are two people. Choose a bus/train with a reputation and an aisle seat if you want eyes on bags. Observation-car Instagram sleepers with bags in the aisle are how stories start. If the laptop is mission-critical, day transfer or private car removes most of that stress. Shoes stay on your feet.