A backpack is a backpack is a backpack

We know that there are tens of thousands of great backpacks out there, all of which are suitable for a specific purpose and serve it well.
In our experience, it can be beneficial to try something new and stray from the beaten path.

We have had the best experience with camera backpacks, which are used by photographers.
They are designed to carry heavy loads and offer reasonable protection against knocks, bumps, and rain.
However, they also come at a price.

Setting aside all discussions and opinions, let's take a look at what we have here.

As you can see, this backpack offers many features.
Its 35-liter volume is a good size to meet many requirements. We use it for longer recording sessions, both indoors and outdoors.
For shorter or medium-length sessions, we use the 28L version, as it is lighter and more than sufficient.
Always keep in mind that you have to carry all that stuff, and every kilogram can feel quite heavy on a long trail. You also have to carry everything back home! ;-)

Sometimes these backpacks come with an additional shoulder bag, as shown here. This feature is very useful and convenient. You can store your "small setup" in it and access it quickly.
This could include a small tripod, a handheld recorder, extra batteries, special microphones (such as contact microphones and geophones), and an impedance converter for piezo-based microphones. Or whatever else you deem necessary.

These partitions are useful in large backpacks. They help you organize your gear and prevent it from shifting around while you walk. They also prevent microphone cables from becoming tangled.
If you don't need a partition, leave it at home! While they are not heavy, they add a few grams of weight and may use space that could be used for something more useful. If you find that your chosen combination of partitions isn't working for you, take a picture and make some notes. Next time, you will do much better.

The external fixing points of such a backpack should also grab your attention. Especially the straps for securing tripods or microphone stands. Independent of where they are located.
You may also want to carry your "dead cats" outside the backpack in a solid plastic bag attached to the front compartment. This saves space inside the backpack and gives you quick access to these items. Or, do whatever works best for you.

Sometimes, though, you may need something between the "big backpack" and the little shoulder bag.
We have backpacks with a volume of just 12 liters, which we use for short field recording sessions lasting a day. They are lightweight, flexible, and provide enough space for the necessary equipment.
No one says you can't use them all at the same time for the same session. But, as already said: You're the one who has to carry it all.