Apples. Though tasty, peaches, pears, and oranges can be messy to eat, and bananas get mushy. Apples can withstand a lot more abuse.
Protein-rich raw, unsalted nuts, such as almonds, sunflower seeds, and walnuts. Tote these for their sheer indestructibility and relative indifference to air exposure.
Dried fruit. To keep the sugars in fruits like raisins from crystallizing, empty a few handfuls into resealable bags. (Toss the less airtight boxes.) For items like mangoes and apples, seek out those with no added sugar, to keep calories down and crunchiness at bay.
Vacuum-sealed tuna packets or tuna-salad kits (complete with mayo and crackers). Like Lunchables, but for grown-ups.
Celery sticks, baby carrots, olives, cherry tomatoes. These veggies can withstand a fair amount of jostling and time away from the refrigerator.
Packets of plain instant oatmeal. Empty one into a travel mug before a flight, ask an attendant for boiling water, and you have a quick breakfast with no cup necessary.
Drinkable yogurt or single-serving containers of applesauce. Punch a straw through the foil and it’s a spillproof, no-utensil healthy snack.
Dried ginger. A sweet snack that can also help keep motion sickness at bay.