This is a wet bag. Not that it is wet mind you.
It is for wet dish towels and dish rags It is lined with more of that Air mattress that you have seen me use here before.  I make dish clothes and so when they need washing I don't have them sitting some wear getting moldy. then when I go down stairs to wash I just grab them all at once. We pull the wash clothes from the bath room and put them in here too.