Wrap the ice pack. Seal the sandwich. Done.

Your ice pack isn’t leaking — it’s condensation. Cold surface hits warm humid air inside the bag, and moisture forms on the pack. It happens to a can of soda too. You can’t stop physics, but you can stop soggy sandwiches.

Wrap the ice pack in a dish towel or a couple of paper towels before it goes in the bag. The cloth catches the sweat, and you’re not wiping out the lunch bag every evening. This is the single best fix and costs nothing.

Second, your food should not be naked in the bag. A sealed container or even a decent Ziploc keeps condensation off the sandwich entirely. If you’re packing bread, the container isn’t optional — it’s the actual answer.

One more thing: if you’re using one of those soft gel packs, they sweat like crazy. The rigid hard-shell ice packs (the plastic brick kind) produce noticeably less condensation. Not zero, but close enough that the paper towel trick becomes overkill.

Paper towel wrap + sealed container, and you’re done. Your sandwich stays dry and your bag stops smelling like a locker room.