I love a packed lunch or a picnic, but what I really hate is a day on the beach when your sandwiches are completely ruined by those tiny grains of sand that just manage to get absolutely everywhere. No matter how hard I try I can't stop the sticky little grains dropping off my fingers onto the food.
Now, I'm not foolish enough to suggest that our plastic lunchboxes are the answer to this problem, but they do have a couple of advantages that help: Firstly they have a good height lip or rim all around to stop the sand just blowing onto the food, and secondly the lie completely flat when open allowing them to be used a as solid tray for the food, rather than just having it lying around on a sandy picnic blanket. If you stick a small packet of wipes in there as well you could solve the problem entirely! Of course the other answer is to avoid sandy beaches entirely: Chesil beach here we come!