Keeping drinks cold

You can buy little coolers or cooler bags and the re-usable ice packs in lots of stores.

My husband and I both carry on a thermos of water with a wedge of lemon to stay hydrated during the flight. Thermos must be empty until you are past security (and the lemon must be already cut up because, a whole lemon could be dangerous although the TSA agent didn't know why and no, it wasn't an agricultural issue ). I buy a cup at say burger king saying I just want a cup of water and then fill up our thermos bottles. They probably wouldn't bug you if you just filled up your thermos directly but that seems a bit cheesy. Anyway we use them during the trip to keep drinks hot/cold. My Zoirushi thermos bottles are practically bullet proof and keep things hot/cold for almost 24 hours.

I often fill a .5 liter bottle with water in the evening and ask the hotel staff to put it in the freezer for me. When I claim it in the morning, it is rock-hard (don't fill it all the way!!!), and takes hours to completely defrost.

It's funny the creature comforts we think we need. Travel gets us out of our comfort zone and broadens our thinking and habits. After your trip, I hope you agree.

If you are having water, red wine or fruit juice with your lunch keeping it cold shouldn't be an issue. Just drink it room temperature. A bonus would be that the cold bier that you might have later in the afternoon in a biergarten after a day of sightseeing will seem all the more refreshing :-)

I go through so much water when hiking that I don't worry if its cold. A bonus of having it room temperature is it doesn't have condensation on it to run down into the rucksack. We refill all day either in bathrooms or at Swiss or Italian fountains.

Our normal picnic stop is at a small grocery store right around lunch time. Germany is going more toward supermarkets but most places will have what we would call a deli in the back where you can pick up 100 grams of sliced meat and/or cheese and some fresh bread rolls. We also pick up cold drinks, beer or wine for our meal, a mustard (that comes in a tube), chocolate, and anything else that looks appetizing. We then wander to a nearby park and eat our meal. My permanent picnic kit is simply a plastic fork and a swiss army knife (purchased there because you can no longer carry on); my wife likes yogurts so she carries both a plastic spoon and fork.