The perfect travel day pack may very well be this Thule Aion 28L Expandable Travel Backpack. When compressed, it has a modest 28-litre capacity, but that can be increased to 32 litres, making it perfect for all kinds of occasions. Unexpanded, it can be used as a day pack when you're out exploring a new destination. When it's expanded, it's roomy enough to be used as a carry-on with all of your essentials.The bag is made from durable, 100% recycled and water-resistant material. There is a large main compartment where you can keep all of your essentials and also an interior padded pocket that can accommodate a 16-inch laptop and a 13-inch tablet. Inside, you can also find an easy-to-clean TPU divider that helps keep things organised and prevents odours, moisture and dirt from spreading. It can also be tucked away if you don't want to use it.Externally, there is a zippered top pocket that can keep all of your smaller items within easy reach, along with side pockets perfect for a water bottle or umbrella. There is also a pass-through panel where you can attach the backpack to the handle of a suitcase. Like other Aion backpacks, this one is also compatible with the Aion Sling Bags, which can double as a supportive hip belt. And, of course, the cool Nutria colour ensures that stains aren't noticeable and that you can easily blend whatever your surroundings.