My backpack has a capacity of 70 liters. A standard backpack typically holds about 30 liters. It features wheels and a pulling handle. Usually, I pull it on wheels, but if the path is uneven or covered with dog waste, I lift the backpack onto my back.
A backpack this large shouldn’t be packed too full. It’s hard to find stuff in there. It can also be too big for sleeping cars on trains and other cramped spaces.
usually take along a passport or ID card
coronavirus test kit and masks
moist towelettes and paper towels
smartphone, tablet, and a blank SIM card to use the tablet as a phone in case the smartphone gets lost or damaged
download apps either at home or during the trip
power bank, 20,000 mA, necessary cables, and a charger and backup charger
travel insurance certificate printed out
European health insurance card
COVID vaccination certificate (if required)
Nowadays, some trains have restrictions on the size of luggage/backpacks. For example, the luggage size for the Spanish Iryo train company is linked to the tickets: Baggage Policy | iryo
Pack clothes for about 10 days. I will wash the clothes at a self-service laundromat. If necessary, I will buy additional clothes.