Not precisely camping, but I thought campers might have good ideas for this!
We are travelling next week to Romania, where the temperatures are expected to be low-mid 30s. DS2 (3.8) is heavily milk dependent when he isn't feeling his best or has had a change in routine. If he wakes up in the night and has trouble sleeping he usually wants milk.
Some of the hotels we are staying in do not have mini bars in the room, so I was hoping to get a flask to keep a litre or so of milk cold, for up to 12 hours in 30+ weather. If it's not drunk in that time, we'd ditch it and get more. It would mostly be used overnight as we can usually find milk during the day for him.
Any suggestions for a flask that will keep its contents cold for long periods of time?