Leave it as you found it

These shelters exist because someone built them and nobody charges for them. They stay open because the people who use them behave as if they'll be back. That's the entire arrangement.

Carry out everything you carried in, including what burns. A fire pit full of foil and a shelf of half-empty gas canisters is how a shelter earns a padlock. Food waste brings animals, and animals bring damage.

Replace the firewood you use, and then some. Somebody dragged that wood uphill so a stranger in trouble would find a dry stove. The next person might be arriving hypothermic at midnight — leave them what you'd want to find.

Make room. If the shelter is full and someone arrives in weather, you shift. Nobody is turned out into a storm because they came late.

Close the door and shutter the windows when you leave, even in summer. Snow and rain do more damage to these buildings than people do — an open door through one winter can end a shelter that stood for forty years.

And if something has changed — a broken stove, a missing roof, a locked door — report it. Accuracy is the one thing a map like this can offer, and it only comes from the people who were actually there.